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OUTLINES 


PRACTICAL  PHYSIOLOGY 


/iDanual  tor  tbe  pb^stoloatcal  Xaboratorp, 


CHEMICAL  AND  EXPERIMENTAL  PHYSIOLOGY,  WITH 
KEFERErCE  TO  PRACTICAL  MEDICINE. 


WILLIAM  STIRLING,  M.D.,  Sc.D., 

BRACKENBURY   PROFESSOR  OF  PHYSIOLOGY  AND   HISTOLOGY  IN  THE   OWENS   COLLEGE, 

AND    PROFESSOR    IN   VICTORIA   UNIVERSITY,    MANCHESTER;     EXAMINER    IN 

PHYSIOLOGY  IN  THE  UNIVERSITIES  OF  EDINBURGH  AND  LONDON. 


THIRD  EDITION,  REVISED  AND  ENLARGED. 

mxvo  289  irilu5tratlon0» 


PHILADELPHIA: 

P.  BLAKISTON'S  SON  &  CO., 

1012  WALNUT    STREET. 
1905. 

535     : 


8  364 


Biomedical 
Libruy 


In 


Ifmflriam 


CARL     LUDWIG, 
MY  REVEKED  AND  BELOVED  MASTEIL 


BOBIt   AT   WiTZENHAUSEH,    29TH    DeOEHBEB,    ISXti 

OiBD  AT  Lxirzia,  28kd  AfBiL,  1896. 


PREFACE  TO  THE  THIRD  EDITION. 


In  the  light  of  extended  experience  in  teaching  Practical 
Physiology,  I  venture  to  submit  a  Third  Edition  of  this  little 
work.  The  essential  features  remain  unchanged;  but  there  has 
been  some  re-arrangement  of  the  subject-matter,  and  many  addi- 
tions have  been  made,  including  a  short  Appendix  on  Recording 
Apparatus. 

In  preparing  the  Chemical  Part,  I  have  made  use  of  the  Text- 
books of  Gamgee,  Halliburton,  Neumeister,  and  Salkowski ;  while, 
for  the  Experimental  Part,  I  found  numerous  valuable  suggestions 
in  the  practical  works  and  syllabuses  of  my  friends,  Professors 
Gotch,  Halliburton,  Fredericq,  and  Dr  Schenk.  I  have  to  express 
my  thanks  to  Professor  Pick  of  Wiirzburg  for  several  improvements 
in  the  Lessons  on  Muscle. 

A  large  number  of  new  woodcuts  have  been  added  (chiefly  in  the 
Experimental  Part) ;  and  for  communications  and  several  original 
drawings — some  of  the  latter  illustrating  new  methods  described 
by  their   authors — I  am  indebted   to  my  friends   juid   colleagues, 


VI  PREFACE. 

Professors  Birch,  Gotch,  Rutherford,  and  Schafer,  Dr  Bayliss,  Dr 
Gregor  Brodie,  and  C.  Herbert  Hurst,  Ph.D.  The  sources  of  the 
other  illustrations  and  methods  are  acknowledged  elsewhere. 

I  have  also  to  thank  my  pupils,  ^lessrs  Moore,  Halstead,  and 
J.  H.  Sheldon,  for  some  of  the  drawings,  and  my  Senior 
Demonstrator,  Dr  J.  A.  Menzies,  for  reading  the  proof  sheets,  and 
for  other  kind  assistance  and  suggestions. 

WILLIAM  STIRLING. 


PHT8I0L0GICi.L  LaBOBATOKT,  OwKNS  C0LLB0>| 

UASCUiSTt^B.,  Augud  1895. 


CONTENTS. 


PAET  I.— CHEMICAL  PHYSIOLOGY. 

UflSOir  PAGES 

I.   THE  PBOTEIDS I-ia 

n.   THB    ALBUMBNOIDS    AND    80MB    NITROQKNOUS    DERIVATIVES    OF 

PBOTEIDS 13-14 

in.    THB  CARBOHYDRATES.           .......           .  1 5-29 

IV.    FATS,   BONE,    AND  EXERCISES 29-33 

V.    THE  BLOOD — COAGULATION— ITS  PROTEIDS             ....  33-43 
VI.    THE  COLOURED    BLOOD-CORPUSCLES — SPECTRA    OF    HEMOGLOBIN 

AND  ITS  COMPOUNDS 43-55 

VIL    WAVE-LENGTHS  —  DERIVATIVES     OF     HEMOGLOBIN— ESTIMATION 

OF  HiEMOGLOBIN 55-6? 

VIII.    SALIVARY  DIGESTION 67-7 1 

IX.    GASTRIC  DIGESTION 71-79 

-        X.    PANCREATIC  DIGESTION 79-86 

XI.    THE  BILE 87-90 

Xn.    GLYCOGEN  IN  THB  LIVER 91-94 

Xin.    MILK,  FLOUR,   AND  BREAD 94-99 

XIV.    MUSCLE 99-103 

XV.    SOME  IMPORTANT  ORGANIC  SUBSTANCES IO3-IO4 

XVL    THE   URINE IO4-IIO 

XVII.    THE  INORGANIC  CONSTITUENTS  OF  THB  URINE     ....  IIO-I16 

XVin.    ORGANIC  CONSTITUENTS  OF  THE   URINE II7-120 

XIX.   VOLUMETRIC  ANALYSIS  FOR  UREA 120-127 

XX.    URIC  ACID— URATES— HIPPURIC  ACID— KREATININ       .           .           .  127-136 

XXI.    ABNORMAL  CONSTITUENTS  OF  THE   URINE 136-139 

XXn,    BLOOD,   BILE,    AND  SUGAR  IN   URINE I4O-I43 

XXni.    QUANTITATIVE  ESTIMATION  OF  SUGAR 143-147 

XXIV.    URINARY    DEPOSITS,    CALCULI,    GENERAL    EXAMINATION    OF  THE 

URINE,    AND  APPENDIX 147- 15^ 


vm  CONTENTS. 


PAET  n.— EXPERIMENTAL  PHYSIOLOGY. 

LKSSOH  PAOB 

XXV.    GALVAKTC  BATTERIES  AND  OALVANOSCOPB  ....      IS7-160 

XXVT.    ELECTRICAL  KEYS— RHEOCHORD 160-166 

XXVn.    INDUCTION  MACHINES— ELECTRODES 166-17O 

XXVIII.    SINGLE     INDUCTION     SHOCKS— INTERRUPTED      CURRENT— BREAK 

EXTRA-CURRENT— HELMHOLTZ'S  MODIFICATION  .  .  .      171-176 

XXIX.    PITHINQ  —  CILIARY     MOTION  —  NERVK-MUSCLB     PRBPARATION— 

NORMAL  SALINE I76-179 

XXX.    NERVE-MUSCLE      PREPARATION  —  STIMULATION       OP      NERVE  — 

MECHANICAL,   CHEMICAL,    AND  THERMAL   STIMULI    .           .           .      179-183 
XXXI.    SINGLE     AND      INTERRUPTED      INDUCTION     SHOCKS — TETANUS- 
CONSTANT  CURRENT 183-187 

XXXn.   RHEONOM— TELEPHONE      EXPERIMENT— DIRECT     AND      INDIRECT 
STIMULATION  OP  MUSCLE— RUPTURINO   STRAIN    OF    TENDON— 

MUSCLE  SOUND— DYNAMOMETERS 187-189 

XXXin.    INDEPENDENT    MUSCULAR    EXCITABILITY— ACTION  OP  CURARE— 

ROSENTHAL'S  MODIFICATION— POHL'S  COMMUTATOR  .  .       19O-194 

XXXIV.    THE   GRAPHIC  METHOD— MOIST  CHAMBER— SINGLE   CONTRACTION 

— "WORK  DONE 194-200 

XXXV.    CRANK-MYOGRAPH — AUTOMATIC  BREAK 2OO-203 

XXXVI.    ISOTONIC     AND   ISOMETRIC    CONTRACTIONS- WORK  DONE— HEAT- 
RIGOR        203-206 

XXXVn.    PENDULUM-MYOGRAPH  —  SPRINQ-MYOGRAPH  —  TIME-MARKER  — 

SIGNAL 206-213 

XXXVin.    INFLUENCE      OP      TEMPERATURE,      LOAD,       AND     VERATRLA.      ON 

MUSCULAR  CONTRACTION 213-216 

XXXIX.    ELASTICITY  AND  EXTENSIBILITY  OF    MUSCLE— BLIX'S  MYOGRAPH      216-218 

XL.    TWO  SUCCESSIVE  SHOCKS— TETANUS 219-223 

XLI.    FATIGUE  OF  MUSCLE 223-224 

XLn.    FATIGUE   OF  NERVE— SEAT  OP  EXHAUSTION          ....      225-226 
XLin.    MUSCLE  WAVE— THICKENING  OP  A  MUSCLE— WILD'S  APPARATUS      226-229 
XLIV.    MYOGRAPHIC      EXPERIMENTS      ON     MAN— BRGOGRAPH— DYNAMO- 
GRAPH       229-231 

XLV.    DIFFERENTIAL      ASTATIC      GALVANOMETER  —  N0N-P0LARI8ABLB 

ELECTRODES — SHUNT — CURRENTS  IN  MUSCLE  ....      231-237 
XLVl.   NERVE-CURRENTS — ELECTROMOTIVE  PHENOMENA  OP  THE  HEART 

— CAPILLARY   ELECTROMETER 237-238 

XLVn.    GALVANl'S  EXPERIMENT— SECONDARY  CONTRACTION  AND  TETANUS 

— PARADOXICAL  CONTRACTION— KUHNE'S   EXPERIMENT     .  .      239-243 

XLVin.    ELECTBOTONUS — ELECTROTONIC  VARIATION  OF  EXCITABILITY      .      243-247 


CONTENTS.  IX 

LESSON  PAOM 

XLix.  pfluger's  law  of  contraction— electrotonio  variation  of 

THE  ELKCTRO-MOTIVITY— RITTER'S  TETANUS    ....      247-250 
L.    VELOCITY   OF    NERVE-IMPULSE   IN  MOTOR  NERVES  OF  FROQ  AND 

MAN— KUHNB'S  gracilis  EXPERIMENT 250-254 

LI.   CONDITIONS  AFFECTING  EXCITABILITY   OF  NERVE  .  .  .      254-258 

UI.   THE   frog's  HEART— BEATING   OF  THE   HEART— EFFECT  OF  HEAT 

AND  COLD— SECTION  OF  THE  HEART 259-262 

LIII.   GRAPHIC     RECORD     OF     THE     FROG'S     HEART-BEAT— EFFECT      OF 

TEMPERATURE 262-265 

LIV.   SUSPENSION    METHODS    FOR    HEART  —  GASKELL'S    HEART-LEVER 

AND  CLAMP 266-270 

LV.  STANNIUS'S     EXPERIMENT  —  INHIBITION  —  LATENT     PERIOD     OF 

HEART-MUSCLE 270-273 

LVI.   CARDIAC  VAGUS    AND    SYMPATHETIC    OF    THE    FROQ  AND  THEIR 

STIMULATION 273-276 

IVn.  ACTION  OF  DRUGS  AND  CONSTANT  CURRENT  ON  HEART— DESTRUC- 
TION OF  CENTRAL  NERVOUS  SYSTEM 277-279 

LVni.   PERFUSION  OP  FLUIDS  THROUGH  THE  HEART— PISTON-RECORDER      279-28 1 
LIX.   ENDO-CARDIAL  PRESSURE — APEX-PREPARATION — TONOMETER       .      281-284 
LX.    HEART-VALVES— ILLUMINATED     HEART— STETHOSCOPE — CARDIO- 
GRAPH—POLYGRAPH—INHIBITION  OF  HEART  ....      284-291 
LXI.    THE  PULSE  —  SPHYGMOGRAPHS  —  SPHYQMOSCOPE  —  PLETHYSMO- 

GRAPH • 291-295 

LXn.   RIGID  AND  ELASTIC  TUBES — THE  PULSB-WAVB — SCHEME  OF  THE 

CIRCULATION — RHEOMETER 295-3OO 

LXm,    CAPILLARY  BLOOD-PRESSURE— LYMPH  HEARTS— BLOOD-PRESSURE 

AND  KYMOGRAPH 3OO-306 

LXIV.    PERFUSION  THROUGH  BLOOD-VESSELS 306-307 

LXV.  MOVEMENTS  OP  THE  CHEST  WALL — ELASTICITY  OF  THE  LUNGS- 
HYDROSTATIC  TEST 308-311 

LXVI.    VITAL     CAPACITY — EXPIRED     AIR — PLEURAL     PRESSURE — GASES 

OF  BLOOD  AND  AIR 311-314 

LXVn.   LARYNGOSCOPE-— VOWELS 315-317 

LXVin.   REFLEX  ACTION— ACTION  OF  POISONS — KNEE-JERK      .  .  .      318-322 

LXIX.    SPINAL  NERVE  ROOTS 322 

LXX.    REACTION  TIME — CEREBRAL  HEMISPHERES  ....      323-328 

LXXI.  FORMATION  OF  AN  IMAGE — DIFFUSION— ABERRATION— ACCOM- 
MODATION —  SCHEINER'S  EXPERIMENT  —  NEAR  AND  FAR 
POINTS— PURKINJE'S      IMAGES— PHAKOSCOPB—ASTIGMATISM— 

PUPIL 329-337 

LXXn.   BLIND     SPOT— FOVEA    CENTRALIS— DIRECT    VISION— CLERK-MAX- 

WELL'S  EXPERIMENT— PHOSPHENES— retinal  SHADOWS  .      337-343 

LXXm.   PERIMETRY— IRRADIATION— IMPERFECT   VISUAL  JUDGMENTS         .      344-35O 


CONTENTS. 

LESSOV  PAGB0 
LXirV.    KiJHNB'S  ARTIFICIAL  BYE—MIHNa  COLOUR  SENSATIONS — COLOUR 

BLINDNESS 350-363 

LXXV.   THE  OPHTHALMOSCOPE—INTRAOCULAR    PRESSURE— OPHTHALMO- 
TONOMETER                 ....  364-367 

LXXVI    TOUCH,   SMELL,  TASTE,   HEARINO 367-372 


^iPFKNDlX        ••••••••••>  373 

/in>is ;••••.  |ga 


LIST  OF  ILLUSTRATIONS. 


VIO.  PAGE 

1.  Apparatus  for  coagulation  temperature.    {Oampee.)     .        •        .        .  ^ 

2.  Apparatus  for  fractional  heat  coagulation.     {Halliburton. )          .         .  u 

3.  Potato  starch 17 

4.  Potato  starch  viewed  with  crossed  Nicols.     (Stirling.)         .         .         .  18 

5.  Dextrose.     {Hill.) 20 

6.  Phenyl-glucosazon.     {Stirling.) 21 

7.  Maltose.     {Hill.) •  ....  23 

8.  Phenyl-maltosazon.    {Stirling.) 23 

9.  Lactose.     {Hill.) 24 

10.  Phenyl-lactosazon. .   {Stirling.)           .......  24 

11.  Cane  sugar.     {Hill.) 24 

12.  Laurent's  polarimeter.     {Laurent. ) 26 

13.  "Wild's  polaristrobometer.     {Hermann  and  Pfister.)     ....  27 

14.  Interference  lines,  seen  with  fig.  13    .         .         •         .         •         •         .28 

15.  Gad's  experiment.     {Stirling,  after  Oad.)  .         .         .   •    .         .         •  3° 

16.  Exsiccator.     {Gscheidlen.) 40 

17.  Apparatus  for  obtaining  clear  serum.     {Drechsel.)       .         .         .         .41 

18.  Bernard's  apparatus  for  estimating  sugar.     {Stirling.)         ...  42 

19.  Incineration  of  a  deposit.     (Gscheidlen.) 43 

20.  Gower's  hsemocytometer 44 

21.  Rat's  haemoglobin  crystals.     {Stirling.) 45 

22.  Spectroscope.     {Brovming.) 46 

23.  Platinum  wire  support  for  sodium  flame.     {Gscheidlen. )      .         .         .46 

24.  Spectra  of  haemoglobin.     (Landois  and  Stirling.)        .        •         .         .  47 

25.  Absorption  by  oxy-haemoglobin.     {Rollett. ) 48 

26.  Absorption  by  reduced  haemoglobin.     {Rollett.) 48 

27.  Hermann's  haematoscope.     {Rollett.) 50 

28.  Spectra  of  derivatives  of  haemoglobin.     {Landois  and  Stirling.)           .  51 

29.  Haemochromogen  apparatus.     {Stirling. )     .         .         .         .         .         .52 

30.  Spectrum  of  methaemoglobin.     {V.  Jaksch.) 52 

31.  Spectroscope  for  wave-lengths.     {Landois  and  Stirling.)     •         •         .  55 

32.  Wave  lengths  of  haemoglobin  and  its  compounds.     {Prey er  and  Gamgee.)   57 

33.  Spectra  of  derivatives  of  haemoglobin.     {Preyer  and  Gamgee.)      .         .  58 

34.  Haemin  crystals.     ( F.  Jaksch. ) 59 

35.  Haemoglobinometer  of  Gowers 60 

36.  Fleischl's  haemometer 61 

37.  Bizzozero's  chromo-cytometer 62 

38.  Several  parts  of  fig.  37 63 

39.  Micro-spectroscope  of  Zeiss 66 


%n 


LIST   OF   ILLUSTRATIONS. 


40.  Part  of  fig,  39.     (Zeiss.)     . 

41.  Saliva  and  buccal  secretion.     (V.  Jaksch.) 

42.  Digestion  bath.     (Stirling.) 

43.  Kiihne's  dialyser.     (Stirling.)     . 

44.  Crystals  of  ty rosin.     (Stirling.) 

45.  Crystals  of  cholesterin.     (Stirling.)    . 

46.  Double-walled  funnel.     (QscheidUn.) 

47.  Hot  air-oven.     (Gscheidlen.) 

48.  Milk  and  colostrum.     (Stirling.) 

49.  Porous  cell  for  filtering  milk.     (Stirling.) 

50.  Lactoscope 

51.  Kreatin.     (Brunton.) 

52.  Urinometer.     (Landois  and  Stirling.) 

53.  Deposit  in  acid  urine.     (Landois  and  Stirling.) 

54.  Deposit  in  alkaline  urine.     (Landois  and  Stirling.) 

55.  Stellar  phosphate.     (V.  Jaksch.) 

56.  Triple  phosphate 

57.  Triple  phosphate.     (V.  Jaksch.) 

58.  Burette  meniscus 

59.  Erdmann's  float 

60.  Urea  and  urea  nitrate.     (Landois  and  Stirling.) 

61.  Urea  oxalate 

62.  Dupre's  urea  apparatus       .... 

63.  Steele's  apparatus  for  urea 

64.  Ureameter  of  Doremus.     (Southull.) 

65.  Hiifner's  apparatus.    (V.  Jaksch.) 

66.  Gerard's  urea  apparatvis.     (Gribbs,  Ouxson  <Si  Co.] 

67.  Uric  acid 

68.  Uric  acid 

69.  Hippuric  acid.     (Landois  and  Stirling.) 

70.  Kreatinin  zinc-chloride.     (Landois  and  Stirling. 

71.  Esbach's  tube.     (V.  Jaksch.) 

72.  Johnson's  picro-saccharimeter 

73.  Einhom's  fermentation  saccharometer.     (Stirling.) 

74.  Sacchar-ureameter.     (Gibbs,  Cuxson  is  Co.) 

75.  Hand  centrifuge.     (Muencke. ) 

76.  Oxalate  of  lime 

77.  Acid  urate  of  ammonium.     ( V. 

78.  Cystin       .... 

79.  Leucin  and  tyrosin     . 

80.  Daniell's  cell.     (Stirling. ) 

81.  Grove's  cell 

82.  Bichromate  cell 

83.  Detector.     (Elliott.) 

84.  Du  Bois  Reymond's  key     . 

85.  Scheme  of  84.     (Stirling. ) 

86.  Scheme  of  84.     (Stirling.) 

87.  Morse  key.     (Stevxirt  and  Gee.) 

88.  Spring  key.     (EllioU.) 

89.  Plug  key 


Jaksch.  ] 


LIST  OF   ILLUSTRATIONS.  XUl 

no.  PAGB 

90.  Simple  rheochord.     {Stirling.)  ....••••  X63 

91.  Simple  rheochord.     {Stirling.) 164 

92.  Rheochord,  Oxford  pattern.     {Stirling.) 165 

93.  Reverser.     {Elliott.) 165 

94.  Du  Bois  Reymond  induction  coil.     {Elliott.) 166 

95.  Ewald's  sledge  coil.     {Hurst.) 168 

96.  Vertical  inductorium •        .         .         .         .  i6g 

97.  Hand-electrodes.     {Stirling.) 169 

98.  Du  Bois  electrodes 170 

99.  Induction  coil  for  single  shocks.     {Stirling.)       .....  17X 

100.  Du  Bois  coil 173 

loi.  Break  exti a-current.     {Stirling.) 173 

102.  Helmholtz's  modification 174 

103.  Equalised  make  and  break  shocks.    {Stirling.) 175 

104.  Brodie's  rotating  key 175 

105.  Frog's  leg-muscles.     {Ecker.)      ........  178 

106.  Frog's  sciatic  nerve.     {Ecker.) 178 

107.  Nerve-muscle  preparation  .........  180 

108.  Straw-flag.     {Stirling.) .  i8i 

109.  Scheme  for  single  induction  shocks.     {Stirlimg.)          ....  183 
no.  Scheme  of  constant  current.     {Stirling.) 185 

111.  Frog's  sartor ius  and  thigh  muscles.     (Ecker.) 186 

112.  Rheonom.     {Stirling.) 188 

113.  Pohl's  commutator.     {Elliott.)   .         • 193 

114.  Scheme  of  curare  experiment 194 

115.  Revolving  cylinder  of  Ludwig 195 

116.  Scheme  of  moist  chamber.     {Stirling.) 197 

117.  Record  of  make  and  break  contractions.     {Stirling.)  ....  199 

118.  Muscle  curve.     {Stirling.) 200 

119.  Crank  myograph.     {Stirling.) ,         ,         .201 

120.  Arrangement  for  automatic  break.     {Stirling.) 202 

121.  Simple  muscle  curve.     {Stirlimg.) 204 

122.  Isotonic  and  isometric  muscle  curves.     {Oad.)    .         .         •        •         .  204 

123.  Scheme  of  Pick's  tension  recorder.     {Schenk.) 205 

124.  Apparatus  for  heat- rigor.     {Ludwig.) 206 

125.  Pendulum -myograph ,         .  207 

126.  Pendulum -myograph  curve.     {Stirling.) 208 

127.  Spring-myograph 208 

128.  Revolving  drum  for  time  relations  of  muscle  curve      ....  209 

129.  Electric  signal.     {Stirling.) 210 

130.  Chronograph.     (Cambridge  Scientific  Instrument  Co.)  »        •         .210 

131.  Chronograph  writing  horizontally.     {Marey.) 211 

132.  Simple  myograph.    {Marey.) .         ,         .  211 

133.  Myograph.     {Fredericq.) 212 

134.  Effect  of  temperature  on  muscle  curve.     {Stirling.)     ....  213 

135.  Muscle  curve  with  load.     {Stirling.) 214 

136.  Veratria  curve.     {Stirling.)        ....•,,.  215 

137.  Veratria  curve.     {Stirling.) 215 

138.  Elasticity  of  a  frog's  muscle.     {Stirling.)    ..••,.  217 

139.  Elasticity  of  india-rubber.     {Stirling.)        .,..,,  217 


XIV  LIST   OF   ILLUSTRATIONS. 

140.  Blix's  myograph.     {Fick.) ,         •  ai8 

141.  Curve  of  superposed  contractions.     [Stirling.)    .         •         •         .         •  aig 

142.  Scheme  for  tetanus.     (Stirling.) 220 

143.  Tetanus  (incomplete)  curves.     {Stirling.) 220 

144.  Tetanus  interrupter.     {Stirling.) 221 

145.  Metronome.     {Petzold.) 222 

146.  Magnetic  interrupter.    {Cambridge  Scientific  Instrument  Co.)      .  223 

147.  Fatigue  curve.     {Stirling.) 224 

148.  Fatigue  curve,  slow  drum.     {Stirling.) 224 

149.  Muscle  wave  apparatus •        ,         .         .  227 

150.  Marey's  registering  tambour 228 

151.  Pince  myographique.     {Marey.)          ..*••..  228 

152.  "Wild's  apparatus.     {Stirling.) 229 

153.  Fick's  tension  myograph.     {Schenk.) 230 

154-  Mosso's  ergograph 231 

155.  Thomson's  galvanometer.     {EUiott.) 232 

156.  Lamp  and  scale  for  155 232 

157.  Non-polarisable  electrodes           ........  232 

X58.  Shunt.     {EUiott.) 234 

159.  Scheme  for  galvanometer.    {Stirling.)         ......  234 

160.  Brush  electrodes.     {V.  Fleischl.) ,         .  236 

161    D'Arsonval's  electrodes.     {Verdin.) 236 

162.  Non-polarisable  nerve  electrodes 238 

163.  Galvani's  experiment.     {Stirling.) 239 

164.  Secondary  contraction            .........  240 

165.  Scheme  of  secondary  contraction.     {Stirling.) 241 

166.  Scheme  of  paradoxical  contraction.    [Stirling.) 241 

167.  Kiihne's  experiment     {Stirling. ) 243 

168.  Scheme  of  electrotonic  excitability.     {Stirling.)           ....  244 

169.  Scheme  of  electro  tonus.     {Stirling.)  .......  244 

170.  Curve  of  electrotonus.     {Stirling.) 245 

171.  Scheme  of  electrotonus.     {Landois  and  Stirling.)       ....  246 

172.  Pohl's  commutator  with  cross-bars 246 

173.  Scheme  of  Pfliiger's  law  of  contraction.     (Stirling.)    ....  247 

174.  Scheme  for  kathodic  stimulation 249 

175.  Du  Bois  Reymond's  rheochord   ........  250 

176.  Scheme  of  velocity  of  nerve-energy.     (Stirling.)          ....  251 

177.  Kiihne's  ^acilis  experiment     (Stirling. ) 253 

178.  Scheme  for  unequal  excitability  of  a  nerve.    (Stirling.)        .         .         .  255 

179.  Scheme  for  Griinhagen's  experiment 257 

180.  Frog's  heart  from  the  front.     (E'^ker. ) 260 

181.  Frog's  heart  from  behind.     (Ecker) 260 

182.  Simple  frog's  heart  lever 263 

183.  Tracing  of  frog's  heart.     (Stirling.) 263 

184-  Effect  of  temperature  on  frog's  heart  tracing.     (Stirling.)    ...  264 

185.  Marey's  heart  lever    ..........  265 

186.  Francois- Frank's  lever  for  heart  of  tortoise.    (Verdin.)        .         ,         .  265 

187.  Gaskell's  lever.    (Stirling.) 266 

188.  Tracing  of  frog's  heart  taken  with  186.     (Stirling.)     ....  266 
Z89.  Heart-tracing,  varying  speed  of  dram.     (Stirling.)      ....  967 


LIST   OF   ILLUSTRATIONa  XV 

no.  FAOI 

190.  Heart-tracing,  effect  of  heat  and  cold.     (Stirling.)       •        •        •        •  267 

191.  Gaskell's  clamp.     {Stirling.) 268 

192.  Tracing  of  auricles  and  ventricle.     {Stirling.) 268 

193.  Gotch's  arrangement  for  excised  heart.     {Stirling.)     ....  269 

194.  Tracing  inhibition  of  heart.     {Stirling.) 272 

195.  Latent  period  of  vagus.     {Stirling.)   ..*....  273 

196.  Scheme  of  frog's  vagus.     {Stirling.) 274 

197.  Vagus  curve  of  frog's  heart.     {Stirling. ) 275 

198.  Scheme  of  frog's  sympathetic.     {Gaskell.) 276 

199.  Effect  of  muscarine  and  atropine  on  the  heart.     (Stirling. )           ,         .  278 

200.  Support  for  frog's  heart.     {Stirling. ) 278 

201.  Staircase  heart-tracing 278 

202.  Kronecker's  frog's  heart  cannula 280 

203.  Heart-tracing  during  perfusion.     (Stirling.) 281 

204.  Scheme  of  Kronecker's  manometer.     (Stirling.)  .....  282 

205.  Scheme  of  Roy's  tonometer.     (Stirling.)     ...,,.  283 

206.  Tonometer.     (Cambridge  Scientific  Instrument  Co.)    ....  283 

207.  Illuminated  ox-heart.     (Fredericq  after  Oad.) 286 

208.  Marey's  cardiograph 287 

209.  Polygraph  of  Rothe 288 

210.  Cardiac  impulse  tracing.     (KnoU.) .   .....,,  289 

211.  Rothe's  tambour 289 

212.  Radial  pulse  and  respirations.     (KnoU. ) 290 

213.  Radial  pulse  and  cardiac  impulse.     (Knoll.) 250 

214.  Marey's  sphygmograph.     (BramweU.) 292 

215.  Sphygmograms.     (Marey.) 292 

216.  Dudgeon's  sphygmograph 293 

217.  Sphygmogram.     (Dudgeon.)       •••••...  293 

218.  Ludwig's  sphygmograph 293 

219.  Arm  support  for  217 294 

220.  Gas-sphygmoscope 295 

221.  Marey's  scheme  of  rigid  and  elastic  tubes 298 

222.  Rheometer        ......••«..  299 

223.  Capillary  pressure  apparatus  (F.  Kries.) 301 

224.  Lymph-hearts.     (Ecker.) •        .         ,         .  30X 

225.  Simple  kymograph  (made  by  Verdin.)        •••••.  302 

226.  Nerves  in  neck  of  rabbit.     (Cyon.) 303 

227.  Shielded  electrodes  as  made  by  Verdin       •••••.  303 

228.  Blood-pressure  tracing  of  dog 304 

229.  Blood- pressure  tracing  of  dog.     (Stirling.)          •         •  ,     •         •         .  305 

230.  Fran9oi8-Frank'8  cannula.     (Verdin.)         ......  306 

231.  Marey's  respiration  double  tambour  .•••*..  308 

232.  Stethographic  tracing.     (Stirling.) .  309 

233.  Marey's  stethograph  (FercZin.) 309 

234.  Stethographic  tracing.     (Knoll.)        . 310 

235.  Miiller's  valves.     (Stirling.)       ........  31a 

236.  Hey  wood's  experiment.     (Stirling.) 313 

237.  Gases  collected  over  mercury.     (Oscheidlen.) 313 

238.  Hem  pel's  apparatus  for  expired  air 314 

239.  Hempol's  absorption  pipette       .         .         ,        ,        ,        ,         ,        .314 


XVI  LIST  OF   ILLUSTRATIONS. 

riG.  FAOB 

24a  View  of  larynx          ..••••••••  316 

241.  Larynx  during  vocalisation 316 

242.  Konig's  apparatus 317 

243.  Reaction  time,  pendulum  method.     {Butherford.)      ....  324 

244.  Result  obtained  with  243.     (Butherford.) 324 

245.  Reaction  lime  for  touch,  sight,  hearing.     {Butherford.)       •         .         .  325 

246.  Reaction  time.     {Stirling.) 326 

247.  Neuramcebimeter.     (Obersteiner.) 326 

248.  Frog's  brain.     {Lavxdois  and  Stirling.) 327 

249.  Scheiner's  experiment 332 

250.  Diffusion.    {Hdmholtz.) 332 

251.  Phakoscope .  334 

252.  Model  of  plates  of  ophthalmometer.     (Aubw,) 334 

253.  Apparatus  for  vision  of  a  point.     {Ludwig. ) 337 

254.  Mariotte's  experiment 338 

255.  Mariotte's  experiment  (another  way) 338 

256.  Blind  spot.     {Helmholtz. ) 338 

257.  VoUanann's  experiment  on  the  blind  spot 339 

258.  Bergmann's  experiment.     {Helmholtz.) 340 

'259.  Disc  for  Talbot's  law.     {Helmholtz.) 342 

260.  Charpentier's  disc  for  "  black  band  " 343 

261.  Charpentier's  disc  for  coloured  field  .......  343 

262.  Priestley  Smith's  perimeter 344 

263.  Scheme  for  wheel  movements  of  eye.     (Hering.)        ....  345 

264.  Irradiation-     {Helmholtz.) 346 

265.  Irradiation.     {Helmholtz.)           ........  346 

266.  Irradiation.     {Helmholtz.) 346 

267.  Imperfect  visual  judgments  of  letters 347 

268.  Zollner's  lines 347 

269.  Imperfect  visual  judgment  of  size 348 

270.  Perception  of  size.     {Helmholtz.)        .......  349 

271.  Spiral  disc  for  radial  movement.     {HelvihoiUz.) 350 

272.  Kiihne's  artificial  eye,  as  made  by  Jung 351 

273.  Apparatus  to  mix  coloured  light.     {Hering.)      .....  352 

274.  Scheme  of  273.     {Hering. ) 352 

275.  Rothe's  rotatory  apparatus 353 

276.  Disc  for  contrast.     (Helmholtz.) 355 

277.  Disc  for  simultaneous  contrast.     {HelmJioltz.) 356 

278.  Eagona  Scina's  experiment.     (Bood.) 356 

279.  Bering's  apparatus  for  278.    {Hering.)       ......  357 

280.  Apparatus  for  simultaneous  contrast.     {Hering.)        ....  357 

281.  Simultaneous  contrast  apparatus.     {Hering.)     .         .         •        .         .357 

282.  Bird  and  cage  experiment 3^' 

283.  Spectrum  top.     {Hurst.)    .         ' 3^3 

284.  Spectrum  top  with  spiral.     {Hurst.) 3^3 

285.  Michel's  carriage  for  rabbit.     {Stirling.) 3^5 

286.  Priestley  Smith's  demonstrating  ophthalmoscope        ....  366 

287.  Aristotle's  experiment 368 

288.  Sherrington's  drum  as  made  by  Palmer 3^5 

289.  Birch's  drum  and  recording  apparatus.     {Birch.)        •        ...  386 


PRACTICAL   PHYSIOLOGY. 


PART  L— CHEMICAL  PHYSIOLOGY. 


LESSON  I. 
THE  PROTEIDS. 


Asa  type  of  the  group  of  proteids  we  may  take  white  of  egg,  egg- 
white,  or  egg-albumin.  In  nature  they  occur  only  as  constituents 
or  products  of  living  organisms.  In  animals  they  form  the  prin- 
cipal soUds  of  the  muscular,  nervous,  and  glandular  tissues  of 
blood-serum  and  lymph.  The  bile,  urine,  tears,  and  sweat,  are  the 
only  animal  fluids  which  normally  do  not  contain  proteids.  Their 
elementary  composition  varies  within  the  following  limits : — 


c. 

H. 

N. 

0. 

s. 

From  50 

6.8 

15.0 

22.8 

0.4  per  cent. 

To       55 

7.3 

18.2 

24.1 

5.0       „ 

They  are  amorphous,  and  for  the  most  part  colloid  bodies.  They 
possess  certain  chemical  reactions  in  common,  and  are  closely 
related  to  each  other.  They  are  insohible  in  alcohol  and  ether, 
some  are  soluble  in  water,  others  insoluble,  while  others  are  soluble 
in  weak  saline  solutions.  They  all  rotate  the  ray  of  polarised  light 
to  the  left,  and  are  thus  laevorotatory.  In  strong  acids  and  alkalies 
they  are  dissolved,  but  they  mostly  undergo  decomposition  in  the 
process.  When  decomposed,  they  yield- a  very  large  number  of  other 
bodies,  so  that  their  constitution  is  exceedingly  complex.  In  the 
body,  after  imdergoing  a  series  of  metabolic  changes,  they  are  ex- 
creted chiefly  in  the  form  of  urea,  and  a  number  of  more  or  less 
closely  related  nitrogenous  bodies.  Besides  the  general  characters 
stated  below,  most  of  them  yield  aromatic  bodies,  such  as  tyrosin 
and  phenol. 


2  PRACTICAL   PHYSIOLOGY.  [L 

1.  Preparation  of  a  Solution  of  "Egg- Alhrnnm— Soluble  in 
Water. — Place  the  unboiled  white  of  an  egg  in  a  porcelain  capsule 
(taking  care  that  none  of  the  yolk  escapes),  and  cut  it  freely  many 
times  with  scissors  to  disintegrate  the  membranes,  and  thus  hberate 
the  albumin.  Add  twenty  volumes  of  distilled  water,  shake  the 
mixture  vigorously  in  a  flask  until  it  froths  freely.  Cork  the  flask 
and  invert  it,  mouth  downwards,  over  a  porcelain  capsule;  the 
froth  and  debris  float  to  the  surface,  and,  after  a  time,  if  the 
cork  be  gently  withdrawn  to  allow  the  fluid  to  escape,  a  sHghtly 
opalescent  fluid  is  obtained.  The  opalescence  is  due  to  the  pre- 
cipitation of  a  small  quantity  of  globulins.  If  the  fluid  be  too 
opalescent,  strain  through  flannel  or  several  folds  of  muslin.  Such 
a  solution  filters  slowly,  so  that  it  is  better  to  employ  several  small 
filters  if  a  clearer  solution  be  required.  If  the  fluid  be  alkahne, 
neutralise  it  with  2  per  cent,  acetic  acid.  Egg-white  contains  about 
11-12  per  cent,  of  egg-albumin,  together  with  small  quantities  of 
globulins,  grape-sugar,  and  mineral  matter. 

General  Reactions. — (A.)  Colour  Reactions. 

(a.)  Xanthoproteic  Reaction. — Add  strong  nitric  acid  =  a 
white  precipitate,  which  on  being  boiled  turns  yellow.  After  cool- 
ing add  ammonia  =  the  yellow  colour  or  precipitate  becomes  orange. 

(b.)  Millon's  Test  =  a  whitish  precipitate  which  becomes  brick- 
red  on  boiling.  A  red  colour  of  the  fluid  is  obtaiued  if  only  a 
trace  of  proteid  be  present. 

Preparation  of  Millon's  Eeagent. — Dissolve  mercury  in  its  own  weight  of 
strong  nitric  acid,  specific  gravity  1.4,  and  to  the  solution  thus  obtained  add 
two  volumes  of  water.  Allow  it  to  stand,  and  aftenvards  decant  the  clear 
fluid  ;  or  take  one  part  of  mercury,  add  two  parts  nitric  acid,  specific  gravity 
1.4  in  the  cold,  and  heat  over  a  water-bath  till  complete  solution  occurs. 
Dilute  with  two  volumes  of  water,  and  decant  the  clear  fluid  after  twelve 
hours. 

(c.)  Piotrowski's  Reaction. — Add  excess  of  strong  solution  of 
caustic  soda  (or  potash),  and  then  a  drop  or  two  of  ver?/  dilute  solu- 
tion of  cupric  sulpliate  (1  per  cent.)  =  a  violet  colour.  The  reaction 
occurs  more  quickly  if  heat  is  apphed,  and  the  colour  deepens. 

The  peptones  and  albumoses  give  a  rose-jrink  colour,  instead  of  a 
violet,  if  only  a  trace  of  copper  sulphate  is  used. 

(B.)  Precipitation. — Peptones  and  albumoses  are  exceptions  in 
many  cases. 

(d.)  The  solution  is  precipitated  by  (i.)  lead  acetate;  (ii.)  mer- 
curic chloride;  (iii.)  picric  acid;  (iv.)  strong  acids,  e.g.,  nitric;  (v.) 
tannin ;  (vi.)  alcohol. 

(e.)  Make  a  portion  strongly  acid  mth  acetic  acid,  and  add 
potassic  ferrocyanide  =  a  white  precipitate. 

(/.)  Saturate  it  with  ammonium  sulphate  by  adding  crystals  of 


I.]  THE   PROTEIDS.  3 

the  salt,  and  shaking  vigorously  in  a  tube  or  flask.  This  precipi- 
tates all  protcids  except  peptones.  Filter ;  the  filtrate  contains  no 
proteids. 

(g. )  By  hydrochloric  acid  in  a  solution  saturated  with  common  salt. 

(h.)  By  alcohol,  except  in  the  presence  of  a  free  alkali. 

(i.)  Precipitate  a  portion  with  (i. )  meta-phosphoric  acid  ;  (ii. )  phosphotung- 
stic  acid,  after  acidulating  with  HCl. 

N.B. — Peptones  are  not  precipitated  by  (e.)  and  (/.). 

(C.)  Coagulation  by  Heat. 

(,;.)  Heat  the  fluid  to  boiling — there  is  no  coagulum  of  albumin 
formed — and  then  add,  drop  by  drop,  dilute  acetic  acid  (2  per 
cent.),  until  a  flaky  coagulum  of  coagulated  insoluble  albumin 
separates. 

The  coagulum  comes  down  about  70°  C.  Unless  the  fluid 
be  acidulated,  the  albumin  does  not  coagulate. 

(k.)  Boil  and  add  nitric  acid  =  a  white  or  yellowish  coagulum. 

(I.)  Acidify  strongly  with  acetic  acid,  add  an  equal  volume  of 
a  saturated  solution  of  sodic  sulphate,  and  boil  =  coagulation. 
This  precipitates  all  proteids  except  peptones.  This  method  and 
the  foregoing  (J.)  are  used  for  separating  the  albumin  in  a  liquid 
containing  it. 

(D.)  (m.)  IndifFusibility. — Place  some  of  the  solution  either  in 
a  dialyser  or  in  a  sausage-tube  made  of  parchment-paper,  and  sus- 
pend the  latter  by  means  of  a  glass  rod  thrust  through  the  tube 
just  below  the  two  open  ends  (Lesson  IX.)  in  a  tall  glass  jar  filled 
with  distilled  water,  so  that  the  two  open  ends  are  above  the  sur- 
face of  the  water.  The  salts  (crystalloids)  diffuse  readily  (test  for 
chlorides  by  nitrate  of  silver  and  nitric  acid),  but  on  applying  any 
of  the  above  tests  no  proteids  are  found  in  the  diftusate.  They 
belong  to  the  group  of  Colloid  bodies.  (Peptones,  however,  are 
diffusible  through  animal  membranes.) 

(E.)  (n.)  Reaction  of  Adamkiewicz. — To  white  of  egg  add  glacial  acetic 
acid,  and  heat  to  get  it  in  solution;  gradually  add  concentrated  sulphuric 
acid  =  a  violet  colour  with  slight  fluorescence. 

(0.)  Liebermann's  Reaction. — "Wash  finely  powdered  albumin  first  with 
alcohol  and  then  with  cold  ether,  and  heat  the  washed  residue  with  concen- 
trated hydrochloric  acid  =  a  deep  violet-blue  colour.  This  is  best  done  in  a 
white  porcelain  capsule,  or  on  a  filter-paper  in  a  funnel  ;  in  the  latter  case, 
the  boiling  acid  is  poured  gently  down  the  side  of  the  filter-paper. 

For  other  colour  reactions  with  cobalt  sulphate  and  NH4HO,  and  KHO  see 
Pickering,  Journ.  of  Phys.,  vol.  xiv. 

2.  Presence  of  Nitrogen  and  Sulphur  in  Albumin. 

(a.)  Place  some  powdered  dried  albumin  in  a  reduction  tube, 
and  into  the  mouth  of  the  tube  insert  (i)  a  red  htmus  paper, 
and  (2)  a  lead  acetate  paper.  On  heating  the  tube,  the  former 
becomes  blue  from  the  escape  of  ammonia,  which  can  also  be 


PRACTICAL   PHYSIOLOGY. 


[t 


smelt  (odour  of  burned  feathers),  and  the  latter  black  from  the 
formation  of  lead  sulphide. 

(b.)  Heat  some  dry  proteid  with  excess  of  soda-hme  in  a  hard 
dry  tube ;  ammonia  vapour  is  evolved. 

(c.)  Place  a  few  grains  of  the  dry  proteid,  with  a 
small  piece  of  metallic  sodium,  in  a  dry  hard  tube, 
and  heat  slowly  at  first,  and  then  strongly.  After 
cooling,  add  carefully  3  cc.  of  water  to  the  NaCy 
residue,  filter,  and  to  the  filtrate  add  a  few  drops  of 
ferric  chloride  and  ferrous  sulphate,  and  then  add 
excess  of  hydrochloric  acid.  If  nitrogen  be  present, 
there  is  a  precipitate  of  Berlin  blue,  sometimes  only 
seen  after  standing  for  a  time. 

{d. )  To  a  solution  of  albumin  add  an  equal  volume 
of  solution  of  caustic  potash  and  a  few  drops  of  lead 
acetate  and  boil  for  some  time  =  slowly  a  brownish 
colouration,  due  to  lead  sulphide. 

3.  Determination  of  Temperature  of  Coagulation 

(fig.  i). — The  reaction  of  the  fluid  must  be  neutral 
or  feebly  acid.      **A  glass  beaker  containing  water 
is  placed  within  a  second  larger  beaker  also  contain- 
ing water,  the  two  being  separated  by  a  ring  of  cork. 
Into  the  water  contained  in  the  inner  beaker  there 
is  immersed  a  test-tube,  in  which  is  fixed  an  accurately 
graduated  thermometer,  provided  with  a  long  narrow 
bulb.      The  solution   of  the  proteid,  of  which  the 
temperature  of  coagulation  is  to  be  determined,  is 
placed    in    the    test-tube,    the  quantity  being  just 
sufficient  to  cover  the  thermometer  bulb.     The  whole 
Fig.  I.— Apparatus  for  De-  apparatus  is  then  gradually  heated,  and  the  experi- 
termining  the  Coagula-  menter  notes  the  temperature  at  which  the  liquid  first 
^''o'leid?'"''  '         shows  signs  of  opalescence  »  {Gamgee). 

4.  Circumstances  Modifying  the  Coagulating  Temperature. — Place  5  cc. 
of  the  solution  of  albumin  in  each  of  three  test-tubes,  colour  them  with  a 
neutral  solution  of  litmus,  and  label  them  A,  B,  C.  To  A  add  a  drop  of  very 
dilute  acetic  acid  (o.  i  per  cent,  acetic  acid  diluted  five  or  six  times);  to  B 
add  a  very  dilute  solution  of  caustic  soda  (o.  i  per  cent,  of  soda  or  potash 
similarly  diluted);  C  is  neutral  for  comparison.  Place  all  three  tubes  in  a 
beaker  with  water  and  heat  them  gradually,  noting  that  coagulation  occurs 
first  in  A,  next  in  C,  and  not  at  all  in  B,  the  alkaline  solution. 


CLASSIFICATION  OF  PROTEIDS. 

5.  I.  Native  Albumins  are  soluble  in  tcater,  in  dilute  saline 
solutions,  in  saturated  solutions  of  sodic  chloride,  and  magnesium 
sulphate,  and  are  not  precipitated  by  alkaline  carbonates,  sodic 
chloride,  or  very  dilute  acids.  They  are  precipitated  by  saturating 
their  solutions  with  ammonium  sulphate.  These  solutions  are 
coagulated  by  heat  at  70°  to   73°  C,  although  the  temperature 


I.]  THE   PROTEIDS.  5 

varies  considerably  with  a  large  number  of  conditions.  When 
dried  at  40°  C.  they  yield  a  clear  yellow  coloured  mass,  "  soluble 
albumin,"  which  is  soluble  in  water. 

(i.)  Egg- Albumin. — Prepare  a  solution  (Lesson  I.  1.). 

{a. )  Evaporate  some  of  the  fluid  to  dryness  at  40°  C.  over  a  water-bath  to 
obtain  "soluble  albumin."  Study  its  characters,  notably  its  solubility  in 
water.  This  solution  gives  all  the  tests  of  egg-albumin.  It  is  more  con- 
venient to  purchase  this  substance. 

{}).)  The  fluid  gives  all  the  general  proteid  reactions. 

{rj)  Precipitate  portions  of  the  fluid  with  strong  mineral  acids, 
including  sulphuric  and  hydrochloric  acids. 

{d.)  Precipitate  other  portions  by  each  of  the  following  : — Mer- 
curic chloride,  basic  lead  acetate,  tannic  acid,  alcohol,  picric  acid. 

(e.)  Take  5  cc.  of  the  fluid,  add  twice  its  volume  of  o.i  per  cent, 
sulphuric  acid,  and  then  add  ether.  Shake  briskly  =  coagulation 
after  a  time,  at  the  line  of  junction  of  the  fluids. 

(/.)  The  solution  is  7iot  precipitated  on  saturation  with  crystals 
of  sodic  chloride  or  magnesic  sulphate,  but  it  is  completely  pre- 
cipitated on  saturation  with  ammonium  sulphate  (NHJ^80^  (com- 
pare "  Globulins  "). 

{g.)  A  solution  containing  1-3  per  cent,  of  salts  coagulates  at 
about  56°  C. 

(2.)  Serum-Albumin. — Blood-serum  (see  "Blood")  contains 
serum-albumin  and  serum- globulin.  Dilute  blood-serum  until  it 
has  the  same  specific  gravity  as  the  egg-albumin  solution.  A  shglit 
opalescence,  due  to  precipitation  of  serum-globulin,  is  obtained. 
Neutralise  the  solution  with  very  dilute  acid  until  a  faint  haziness 
is  obtained. 

Eepeat  the  tests  for  egg-albumin,  and,  in  addition,  with  undiluted 
blood-serum. 

(/?.)  Add  crystals  of  MgSO^  to  saturation,  shaking  the  flask 
vigorously  to  do  so  =  a  white  precipitate  of  serum-globulin.  Filter. 
The  filtrate  contains  serum-albumin. 

{i.)  Saturate  serum  with  (]SrH^)^S04  =  white  precipitate  of  both 
serum-albumin  and  serum-globulin.  Filter.  The  filtrate  contains 
no  proteids. 

EGG-ALBUMIN.  SERUM-ALBUMIN. 

(i.)  Readily   precipitated    by  (i.)  It  is  also  precipitated  by 

hydrochloric  acid,  but  the  pre-  hydrochloric   acid,   but   not   so 

cipitate  is  not  readily  soluble  in  readily,  while  the  precipitate  is 

excess.  soluble  in  excess. 

(ii.)  A  non-alkahne   solution  (ii.)  It  is  not  coagulated  by 

is  coagulated  by  ether.  ether. 


6  PRACTICAL   PHYSIOLOGY.  [l. 

EGG-ALBUMIN.  SERUM-ALBUMIN. 

(iii.)  The     precipitate      with  (iii.)  The   corresponding  pre- 

nitric  acid  is  sohible  with  diih-  cipitate   is   much  more  soluble 

culty  in  excess  of  the  acid.  in  excess  of  acid. 

(iv.)  The  precipitate  obtained  (iv.)  The  corresponding  pre- 

by  boiling  is  but  shghtly  soluble  cipitate    is    soluble    in    strong 

in  boiling  nitric  acid.  nitric  acid. 

(v.)  Its  solution  is  not  pre-  (v.)  Gives  the  same  reactions 

cipitated    by    MgSO^,    but    is  as  in  (  5,  I.  /.). 
completely      precipitated       by 
(NH,),SO,. 

[(vi.)  When   injected    under  [(vi.)  When   injected    under 

the  skin,  or  introduced  in  large  the  skin,  it  does  not  appear  in 

quantities  into   the  stomach  or  the  urine.] 
rectum,  it  is  given  off  by  the 
urine.] 

(3.)  Lact-Albumin,  see  "Milk." 

6.  II.  Globulins  are  insoluble  in  pure  water,  soluble  in  dilute 
saline  solutions — e.g.^  NaCl,  MgSO^,  (^11^)2804 — but  insoluble  in 
concentrated  or  saturated  solutions  of  neutral  salts.  Their  solu- 
tions in  these  salts  are  coagulated  by  heat.  They  are  soluble  in 
dilute  acids  and  alkalies,  yielding  acid-  and  alkali-albumin  respec- 
tively. Most  of  them  are  precipitated  from  their  saline  solution  by 
saturation  with  sodic  chloride,  magnesium  sulphate,,  and  some  other 
neutral  salts. 

(•I.)  Serum-Globulin.— It  forms  about  half  of  the  total  proteids 
of  blood-serum.  It  is  insoluble  in  water,  readily  soluble  in  dilute 
saline  solutions  (XaCl,  MgSO^).  Its  solutions  give  the  general 
reactions   for   proteids.     Its  NaCl   solution   coagulates   at    about 

75°  c. 

(a.)  Neutralise  5  cc.  of  blood-serum  with  a  few  drops  of  dilute 
sulphuric  acid  (o.i  per  cent.),  then  add  75  cc.  of  distilled  water, 
and  allow  the  precipitate  to  settle.  Pour  off  the  fluid  and  divide 
the  precipitate  into  two  portions,  noting  that  it  is  insoluble  in 
water,  but  soluble  in  excess  of  acid. 

{h.)  Boil  a  portion  of  the  neutrahsed  fluid  =  coagulation. 

{(•.)  Saturate  blood-serum  in  a  test-tube  with  magnesium  sulphate, 
shaking  briskly  for  some  time.  Serum-globulin  separates  out  and 
floats  on  the  surface.  Filter,  and  test  the  filtrate  for  serum- 
albumin. 

{d.)  Place  5  cc.  of  blood-serum  in  a  tube,  and  pour  a  saturated 
solution  of  magnesium  sulphate  down  the  side  of  the  tube  to  form 
a  layer  at  the  bottom  of  the  tube.  Where  the  two  fluids  meet 
there  is  a  white  deposit  of  serum-globulin. 


I.]  THE  PROTEIDS.  7 

(e )  Saturate  blood-serum  with  crystals  of  sodium  chloride  or 
neutral  ammonium  sulphate  =  separation  of  serum-globulin,  which 
floats  on  the  surface. 

(/.)  Precipitate  the  serum-globulin  with  magnesium  sulphate, 
and  filter.  To  the  filtrate  add  sodium  sulphate  in  excess,  which 
gives  a  further  precipitate.  The  filtrate  may  still  give  the  reactions 
for  proteids. 

(2.)  Fibrinogen,  see  "  Blood." 

(3.)  Myosin,  see  "  Muscle." 

(4.)  Vitellin.— Shake  the  yolk  of  an  egg  with  water  and  ether,  as  long  as 
the  washings  show  a  yellow  colour.  Dissolve  the  residue  in  a  minimal 
amount  of  10  per  cent,  sodium  chloride  solution.  Pour  it  into  a  large  quan- 
tity of  water,  slightly  acidulated  with  acetic  acid  =  white  precipitate  of 
impure  vitellin. 

{a. )  Dissolve  some  of  the  precipitate  in  a  very  weak  saline  solution,  and 
observe  that  it  is  not  reprecipitated  by  saturation  with  sodic  chloride. 

{b.)  Test  some  of  the  weak  saline  solution  =  coagulation  about  75"  C. 

(c.)  The  precipitate  is  readily  soluble  in  .1  per  cent,  hydrochloric  acid,  and 
also  in  weak  alkalies. 

(5.)  Crystallin  is  obtained  from  the  crystalline  lens. 

(6. )  Globin  the  proteid  constituent  of  haemoglobin. 

7.  III.  Derived  Albumins  (Albuminates)  are  compounds  of 
proteids  with  mineral  substances.  Those  produced  by  the  action 
of  acids  or  alkalies  on  albumins  and  globuHns,  yield  respectively 
acid-albumin  and  alkaU-albumin.  They  are  insoluble  in  pure  water 
and  in  solutions  of  sodium  chloride,  but  readily  soluble  in  dilute 
hydrochloric  acid  and  dilute  alkaUes.  The  solutions  are  not  coagu- 
lated by  heat. 

(i.)  Alkali-Albumin  or  Alkali- Albuminate. 

{a.)  To  dilute  egg-albumin  add  a  few  drops  of  o.i  per  cent, 
caustic  soda,  and  keep  it  at  40°  C.  for  5-10  minutes  =  alkali- 
albumin.     Boil  the  fluid ;  it  does  not  coagulate. 

(6.)  Test  the  reaction ;  it  is  alkaline  to  litmus  paper. 
.(c.)  Cool    some    of    the    alkali-albumin,    colour   it   with   Htmus 
solution,  and  neutralise  carefully  with  o.  i  per  cent,  sulphuric  acid  =  a 
precipitate  on  neutralisation,  which  is  soluble  in  excess  of  the  acid, 
or  of  alkali. 

{(l.)  Repeat  (c);  but,  before  neutralising,  add  a  few  drops  of 
sodium  phosphate  solution  (10  per  cent.),  and  note  that  the 
alkaline  phosphates  prevent  the  precipitation  on  neutralisation, 
until  at  least  sufficient  acid  is  added  to  convert  the  basic  phosphate 
into  acid  phosphate.  The  solution  must  be  decidedly  acid  before  a 
precipitate  is  obtained. 

(e.)  Precipitate  by  saturating  it  with  crystals  of  common  salt  or 
magnesium  sulphate. 

(/.)  Lieberkiihn's  Jelly  is  a  strong  solution  of  alkaH-albmnin. 


8  PRACTICAL   PHYSIOLOGY  [L 

Place  undiluted  egg-white  in  a  test-tube,  and  add  strong  caustic 
potash.  Tlie  whole  mass  becomes  a  jelly,  so  that  the  tube  can  be 
inverted  without  the  mass  falhng  out, 

{(J.)  Its  solution  gives  the  general  reactions  for  proteids  under 
1  (A.). 

(2.)  Acid- Albumin  [or  Syntonin]. 

Preparation — (A.)  To  dilute  egg-albumin,  add  o.i  per  cent,  sul- 
phuric acid,  and  warm  gently  for  several  minutes  =  acid-albumin. 

(B.)  To  finely  minced  muscle,  e.g.,  of  frog,  add  ten  times  its  volume  of 
dilute  hj^drochloric  acid  (4  cc.  of  acid  in  i  Utre  of  water),  and  allow  it  to 
stand  for  several  hours,  taking  care  to  stir  it  frequently  ;  filter,  the  filtrate 
is  a  solution  of  a  globulin  combined  with  an  acid,  and  has  been  called 
syntonin. 

(C.)  Allow  concentrated  hydrochloric  acid  to  act  on  fibrin  for  a  time,  and 
filter. 

(D.)  It  may  be  prepared  by  dissolving  myosin  in  excess  of .  i  per  cent.  HCl, 
and  after  a  time  neutralising  the  solution  with  sodic  carbonate. 

(E. )  To  undiluted  egg-white,  add  acetic  acid  =  a  jelly  of  acid -albumin. 

Use  the  clear  filtrate  from  (A.)  or  (B.)  for  testing. 

(a.)  The  reaction  is  acid  to  Htmus  paper. 

(h.)  Boil  the  solution ;  it  does  not  coagulate. 

(c.)  Add  htmus  solution,  and  neutrahse  with  very  dilute  caustic 
soda  =  a  precipitate  soluble  in  excess  of  the  alkali  or  acid. 

{d.)  Kepeat  (c),  but  add  sodium  phosphate  before  neutrahsing ; 
the  acid-albumin  is  precipitated  when  the  fluid  is  neutralised; 
so  that  sodium  phosphate  does  not  interfere  with  its  precipita- 
tion. 

(e.)  Add  strong  nitric  acid  =  a  precipitate  which  dissolves  on 
heating,  producing  an  intense  yellow  colour. 

( /".)  It  is  precipitated  like  globulins  by  saturation  with  neutral  salts,  e.g., 
XaCl,  MgSO^,  (NH4).,S04. 
(g.)  Boiled  with  lime-water = partial  coagulation. 

8.  IV.  Caseinogen,  the  chief  proteid  of  milk  was  formerly 
regarded  as  a  derived  albumin.  It  is  precipitated  by  acid.  Like 
globulins  it  is  precipitated  by  saturating  milk  with  NaCl  or  MgSO^, 
but  it  is  not  coagulated  by  heat.     (See  "  Milk.") 

9.  V.  Proteoses  or  Albumoses. — In  the  peptic  and  tryptic 
digestion  of  pioteids  these  bodies  are  formed  as  intermediate  pro- 
ducts. In  peptic  digestion  of  albumin,  acid-albumin  is  first  formed, 
and  finally  peptone.  Between  the  two  is  the  group  of  proteoses  or 
albumoses.  There  are  several  of  them,  and  they  were  formerly 
grouped  together  as  hemi-albumose.  These  proteoses  have  been 
subdivided  into  albumoses,  globuloses,  caseoses,  &c.,  according  as 
they  are  derived  from  albumin,  globulin,  or  casein.  (See  "  Diges- 
tion.")     Witte's    peptone    usually   contains   a   small   amount    of 


I.]  THE   PROTEIDS.  9 

peptone,  and  much  albumose.  ]|)issolve  some  of  this  body  in  warm 
water,  or  preferably  in  lo  per  cent,  sodium  chloride. 

(a.)  They  are  soluble  in  water;  not  coagulated  by  heat;  and 
are  precipitated  by  saturation  with  neutral  ammonium  sulphate. 
The  precipitate  with  (NH^)^S04  partly  disappears  on  heating,  and 
reappears  on  cooUng.  They  are  precipitated  but  not  coagulated 
by  alcohol. 

(b.)  Add  nitric  acid  =  a  white  precipitate  which  dissolves  witli 
heat  (yellow  fluid)  and  reappears  on  coohng.  Run  tap  water  on 
the  tube,  the  precipitate  reappears.  This  is  a  characteristic  re- 
action, and  occurs  best  in  the  presence  of  NaCl. 

(c.)  It,  like  peptone,  gives  a  rosy -pink  with  Piotrowski's  test. 

{d.)  It  is  precipitated  by  acetic  acid  and  ferrocyanide  of  potas- 
sium, but  the  precipitate  disappears  on  heating,  and  reappears  on 
coohng. 

(e.)  It  is  precipitated  by  acetic  acid  and  saturation  with 
NaCl.  The  precipitate  disappears  on  heating,  and  reappears  on 
cooling. 

10.  VI.  Peptones  are  hydrated  proteids,  and  are  usually  produced 
by  the  action  of  proteolytic  ferments  on  proteids.  They  are  exceed- 
ingly soluble  in  water.  Their  solutions  are  not  precipitated  by 
sodic  chloride,  acids,  or  alkalies,  nor  are  they  coagulated  by  heat. 
They  are  precipitated  by  tannic  acid,  and  with  difficulty  by  a  large 
excess  of  absolute  alcohol.     !N"ot  precipitated  by  (NH^)^SO^. 

Preparation  (see  "  Digestion  "). — For  applying  the  tests  dissolve 
a  small  quantity  of  Darby's  fluid  meat  or  commercial  peptone  in 
warm  water.  Commercial  peptone  contains  only  a  small  amount 
of  peptone,  and  much  albumose. 

{a.)  Boil  a  portion  ;  it  is  not  coagrdated. 

{h.)  Xanthoproteic  Reaction. — Add  nitric  acid,  and  boil  =  a 
faint  yellowish  colour,  and  rarely  any  previous  precipitate ;  cool, 
and  add  ammonia  =  orange  colour. 

(c.)  Acidify  strongly  with  acetic  acid,  and  add  ferrocyanide  of 
potassium  =  no  precipitate. 

{(1.)  Test  separate  portions  with  tannic  acid;  potassio-mercuric 
iodide ;  mercuric  chloride ;  picric  acid  (saturated  solution) ;  and 
lead  acetate.  Each  of  these  causes  a  precipitate.  In  the  case  of 
picric  acid  the  precipitate  disappears  on  heating,  and  reappears  on 
cooling. 

(e.)  Biuret  Reaction. — Add  excess  of  caustic  sodn,  and  then  a 
few  drops  of  very  dilute  solution  of  copper  sulphate  =  a  rose  colour ; 
on  adding  more  copper  sulphate,  it  changes  to  a  violet. 

(/.)  Add  a  drop  or  two  of  Fehling's  solution  =  a  rose  colour;  add 
more  I^ehHng's  solution  it  changes  to  violet. 

{(/.)  Neutralise  another  portion  =  no  precipitate. 


lO  PRACTICAL   PHYSTOLOQY.  [T. 

(/?.)  Add  excess  of  absolute  alcohol  =  a  precipitate  of  peptone, 
but  not  in  a  coagulated  form. 

.  (/.)  It  is  not  precipitated  by  saturation  with  sodic  chloride  or 
magnesic  sulphate,  nor  by  boiling  with  sodic  sulphate  and  acetic 
acid. 

(./.)  Pure  peptone  is  not  precipitated  by  saturation  with  neutral 
sulphate  of  ammonia.  N.B. — The  other  proteids  are.  Hence  this 
5alt  is  a  good  reagent  for  separating  other  proteids,  and  thus  leaving 
the  peptones  in  solution. 

(A'.)  It  also  gives  ^Slillon's  test. 

(l.)  Dififusibility  of  Peptones.  —Place  a  solution  of  peptones  in 
a  dialyser  covered  with  an  animal  membrane,  as  directed  in  Lesson 
I.  1  (D.)  (;??.),  and  test  the  ditfusate  after  some  time  for  peptones. 
Peptones  do  not  dififuse  through  a  parchment  tube. 

{in.)  Saturate  the  solution  of  commercial  peptones  with  (NH^).^ 
SO^  =  a  precipitate  of  albumoses  or  proteoses.  Filter.  The  filtrate 
contains  the  pare  peptone. 

11.  VII.  Coagulated  Proteids  are  insoluble  in  water,  weak 
acids,  and  alkahes,  and  are  dissolved  when  digested  at  35°  to  40°  C. 
in  gastric  juice  (acid  medium),  or  pancreatic  juice  (alkaline 
medium),  forming  first  proteoses  and  finally  peptones.  They  give 
^lillon's  reaction. 

There  are  two  subdivisions  : — 

(A.)  Proteids  coagulated  by  Heat. 

Preparation. — Boil  wliite  of  es^g  hard,  and  chop  up  the  white. 

{a.)  Test  its  insolubility  in  water,  weak  acids,  and  alkalies. 

{h.)  It  is  partially  soluble  in  acids  and  alkalies,  when  boiled  for 
some  time. 

(c.)  Bruise  some  of  the  sohd  boiled  white  of  egg,  diffuse  it  in 
water,  and  test  it  with  Millon's  reagent. 

('/.)  For  the  effect  of  the  digestive  juices  see  "Digestion." 

(B. )  Proteids  coagulated  by  Ferment  Action. 

(i.)  Fibrin  is  insoluble  in  water  and  in  weak  solutions  of 
common  salt.  "When  prepared  from  blood,  and  washed,  it  is  a 
wliite,  fibrous,  soft,  and  very  elastic  substance,  which  exliibits 
fibrillation  under  a  high  magnifying  power  (see  "  Blood  "). 

(rt.)  Place  well-washed  fibrin  in  a  test-tube,  add  o.i  per  cent, 
hydrochloric  acid.  The  fibrin  swells  up  and  becomes  clear  in  the 
cold,  but  does  not  dissolve. 

{h.)  Repeat  (a.),  but  keep  on  a  water-bath  at  60°  C.  for  several 
hours ;  filter,  and  test  the  filtrate  for  acid-albumin  by  neutraUsation 
with  very  dilute  potash. 

{':.)  To  a  very  dUute  solution  of  copper  sulphate  in  a  test-tube, 
add  fibrin.  The  latter  becomes  greenish,  wlule  the  fluid  ia 
decolourised.     Add  caustic  soda,  the  flake  becomes  violet 


«•] 


THE   PROTEIDS. 


II 


(d.)  For  the  eflFect  of  a  dilute  acid  and  pepsin  (see  "Digestion").  These 
"digest"  fibrin,  and  convert  it  into  proteose,  and  ultimately  into  peptone. 

(e.)  It  decom{)Oses  hydric  ])eroxide,  and  turns  freslily-prepared  tincture  of 
guaiacum  blue  (see  "  Blood"). 

(/.)  Digest  fibrin  in  lo  per  cent,  sodium  chloride  for  two  days.  A  small 
part  is  dissolved  ;  boil  the  fluid  =  coagulation. 

(ii.)  Myosin  (see  "Muscle"), 
(iii.)  Casein  (see  "Milk"), 
(iv.)  Gluten  (see  "Bread"). 

12.  VIII.  Lardacein,  or  Amyloid  Substance. —This  occurs  in  organs,  e.g., 
liver  and  kidney,  undergoing  the  pathological  degeneration  known  as  amyloid, 
waxy  or  wax  like,  or  albumenoid  disease.  It  is  insoluble  in  dilute  acids  or 
alkalies,  and  it  is  not  acted  on  by  the  gastric  juice.  It  gives  several  distinct 
reactions,  not  stains,  with  certain  staining  fluids. 

(a.)  A  solution  of  iodine  in  iodide  of  potassium  gives  a  deep  brown  or 
mahogany  stain  when  poured  on  a  section  of  a  fresh  waxy  organ. 

(b.)  With  iodine  and  sulphuric  acid  occasionally  a  blue  reaction  is  obtained. 

(c.)  Methyl-violet  and  gentian-violet  give  a  rose-pink  reaction  with  the 
waxy  parts,  while  others,  i.e.,  the  healthy  parts  of  an  organ,  give  diflerent 
shades  of  blue  or  purple. 


FlO.  2. — Apparatus  of  Halliburton  for  Fractional  Heat  Coagulation  of  Proteida.  T.  Tap 
for  Water;  C.  Copper  vessel  with  spiral  tube;  a.  Inlet,  and  b.  Outlet-tube  to  the 
llask  ;  t.  Test  tube,  with  fluid  and  thermometer. 

13.  Fractional  Heat  Coagulation,  e.g.,  of  blood-sorum.  — The  serum  or 
other  fluid  containing  proteid  is  heated  until  a  flocculent  precipitate  occurs. 
Filter.  The  filtrate  is  again  heated  to  a  higher  temperature,  until  a  similar 
precipitate  appi  ars.  This  precipitate  is  filtered  off,  and  the  above  process 
repeated,  until  the  liquid  is  free  of  proteid. 

The  arrangements  shown  in  fig.  i  may  be  used,  but  the  rise  of  temi)erature 
takes  place  rather  too  slowly,  and  it  is  difficult  to  maintain  the  temperature 
constant  for  a  considerable  length  of  time  when  one  is  investigating  a  large 
number  of  fluids.  The  following  apparatus  used  by  Halliburton  (fig.  2)  is 
more  convenient.  "A  glass  flask  suj)ported  on  a  stand  ;  down  its  neck  is 
placed  a  test-tube,  in  which  again  is  jjlaced  the  liquid  under  investigation  in 
sufficient  quantity  to  co^er  the  bulb  of  a  thermometer  placed  in  it.  The  flask 
is  kept  filled  with  hot  water,  and  this  water  is  constantly  flowing."  It 
enters  by  (a),  passing  to  the  bottom  of  the  flask,   and  leaves  at  {0).     The 


12  PRACTICAL   PHYSIOLOGY.  [l. 

water  is  heated  by  passing  through  a  coil  of  tubing  contained  in  a  copper 
vessel,  not  unlike  Fletcher's  hot-water  apparatus.  The  Huid  to  be  tested 
must  be  well  stirred  by  the  thermometer  during  the  progress  of  the  experi- 
ment. 

In  carrying  out  the  experiment  the  following  precautions  are  necessary, 
viz.,  to  keep  the  fluid  under  investigation  as  nearly  as  possible  always  of  the 
same  reaction,  as  one  of  the  important  conditions  inHuencing  the  temperature 
of  coagulation  of  a  liquid  is  the  amount  of  free  acid  present. 

Use  2  per  cent,  acetic  acid,  and  place  it  in  a  burette.  It  is  dropped  into 
the  fluid  from  tlie  burette.  The  proportion  is  about  one  drop  ot  this  dilute  acid 
— after  neutrality  is  reached— to  3  cc.  of  liquid.  The  acidity  of  the  liquid  is 
tested  by  sensitive  litmus  papers.  The  liquid  must  be  kept  at  a  given 
temperature  for  at  least  five  minutes,  to  ensure  complete  precipitation  of  the 
proteid  at  that  temperature. 

On  heating  certain  solutions  containing  certain  proteids,  as  the  tempera 
ture  of  the  fluid  is  raised,  a  faint  opalescence  appears  first,  and  then,  at  a 
higher  temperature,  masses  or  flocculi  separate  out,  usually  somewhat 
suddenly,  from  the  fluid. 

The  temperature  at  which  coagulation  of  what  is  apparently  one  and  the 
same  proteid  occurs  varies  wth  a  large  number  of  conditions.  Not  only  have 
diflerent  proteids  diff'erent  coagulating  points,  which,  however,  can  hardly  in 
the  light  of  recent  researches  be  called  "specific  coagulation  temperatures," 
but  the  coagulating  temperature  of  any  one  proteid  varies  with  the  rapidity 
with  which  coagulation  takes  place  ;  the  proteid  coagulates  at  a  higher 
temperature  when  the  fluid  is  heated  quickly  than  if  it  be  heated  slowly. 
It  also  varies  with  the  amount  of  dilution,  the  coagulating  point  being  raised 
by  dilution.  The  eHects  of  salts  and  acids  in  altering  the  coagulation  point 
are  well  known. 

14.  Removal  of  Proteids. — The  following,  amongst  other  methods, 
are  used  for  removing  proteids  from  liquids  containing  them.  In 
tliis  way  other  substances  present  may  be  more  easily  detected. 

Wenz^s  Method. — Saturate  with  (NHj)^  SO4.  This  precipitates  all  proteids 
except  peptones. 

By  Boiling. — Acidulate  faintly  with  acetic  acid  and  boil.  This  removes 
globulins  and  albumins. 

Brackets  Mel  hod. — Acidulate  with  HOI,  and  then  add  potassio-mercuric 
iodide  (see  "  Liver  "). 

By  Alcohol. — Acidify  feebly  with  acetic  acid,  add  several  volumes  of 
absolute  alcohol.     After  24  hours  all  proteid  is  precipitated. 

Oirgensohu's  Metho'l. — Mix  the  solution  with  half  its  volume  of  a  saturated 
solution  of  sodium  chloride,  and  add  tannic  acid  in  slight  excess.  This  pre- 
cipitates all  proteids. 

There  are  other  methods  in  use. 


n.]  THE  ALBUMENOIDS.  I3 


LESSON  n. 

THE  ALBUMENOIDS. 

The  group  of  albmnenoids  includes  a  number  of  bodies  which 
in  their  general  characters  and  elementary  composition  resemble 
proteids,  but  differ  from  them  in  many  respects.  They  are  amor- 
phous. Some  of  them  contain  sulphur,  and  others  do  not.  The 
decomposition-products  resemble  the  decomposition-products  of 
proteids. 

1.  I.  Gelatin  is  obtained  by  the  prolonged  boiling  of  connective 
tissues,  e.g.^  tendon,  ligaments,  bone,  and  from  the  substance 
"  Collagen,"  of  which  fibrous  tissue  is  said  to  consist. 

Preparation  of  a  Solution. — Make  a  watery  solution  (5  per 
cent.)  by  allowing  it  to  swell  up  in  water,  and  then  dissolving  it 
with  the  aid  of  heat. 

(A.)  (c/.)  It  is  insoluble,  but  swells  up  in  about  six  times  its 
volume  of  cold  water. 

{h.)  After  a  time  heat  the  gelatin  swollen  up  in  water;  it  dis- 
solves.    Allow  it  to  cool ;  it  gelatinises. 

(B.)  With  General  Proteid  Tests. 

(c.)  Xanthoproteic  Test.— Add  nitric  acid  and  boil  =  a  Hglit 
yellow  colour  with  no  previous  precipitate;  the  fluid  becomes 
orange  or  rather  lemon-coloured  on  adding  ammonia. 

(d.)  Millon's  Eeagent  =  no  pinkish-red  precipitate  on  boihng. 
This  shows  the  absence  of  the  tyrosin  group  in  the  gelatin  molecule. 
This  reaction  may  be  obtained  with  commercial  gelatin,  but  not 
with  pure  gelatin,  so  that  the  reaction  if  obtained  is  due  to 
impurities. 

{e.)  It  gives  a  blue- violet,  rather  than  a  violet  colour,  with  NaHO 
and  CUSO4. 

(/■.)  It  is  not  precipitated  by  acetic  acid  and  potassic  ferrocyanide 
(unlike  albumin). 

{g.)  It  is  not  coagulated  by  heat  (unlike  albumin). 

{h.)  It  is  not  coagulated  by  boiling  with  sodic  sulphate  and  acetic 
acid  (unlike  albumin). 

(i.)  It  is  precipitated  by  saturation  with  MgSO^  or  (^11^)2804. 

(C.)  Special  Reactions. 

(y.)  It  is  not  precipitated  by  acids  (acetic  or  hydrochloric),  or 
alkalies,  or  lead  acetate. 

(A*.)  Add  mercuric  chloride  =  no  precipitate  (unlike  albumose  and 
peptone). 


14  PRACTICAL   PHYSIOLOGY.  [ll. 

(/.)  Add  tannic  acid  =  copious  white  precipitate,  insoluble  in 
excess. 

(m.)  Add  picric  acid  (saturated  solution)  =  yellowish-white  pre- 
cipitate, wliich  disappears  on  heating  and  reappears  on  cooling. 

(w.)  It  is  precipitated  by  alcohol,  and  also  by  platinic  chloride. 

2.  II.  Chondrin  is  obtained  by  the  prolonged  boiling  of  cartilage, 
which  largely  consists  of  the  substance  "  Chondrigen." 

Preparation. — Costal  cartilages  freed  of  their  perichondrium  and  cut  into 
small  pieces  are  boiled  for  several  hours  in  water,  when  an  opalescent  fluid, 
which  gelatinises  on  cooling,  is  formed. 

(a.)  Add  acetic  acid  =  a  white  precipitate,  soluble  in  great  excess. 

{b.)  Dilute  mineral  acids  =  white  precipitate,  readily  soluble  in  excess. 

{c.)  It  is  not  precipitated  by  acetic  acid  and  potassic  ferrocyanide. 

3.  III.  Mucin,  see  "SaHva."  It  is  also  found  in  the  ground 
substance  of  connective  tissue  and  tendon.  There  are  probably 
several  mucins.  On  heating  with  dilute  HgSO^  they  yield  a  reduc- 
ing sugar,  and  they  are  regarded  as  glucosides,  compounds  of  a 
proteid  (globulin  *?)  with  animal  gum. 

(rt.)  They  make  fluids  viscid  and  slimy. 

(b.)  Cut  a  tendon  into  pieces  and  place  it  for  3  days  in  lime-water.  The 
lime-water  dissolves  the  mucin.     Add  acetic  acid  =  precipitate  of  mucin. 

4.  IV.  Elastin  occurs  in  elastic  tissue,  ligamentum  nuchas,  and 
ligamenta  subflava,  &c. 

Preparation. — Boil  the  fresh  ligamentum  nuchae  of  an  ox  successively  in 
alcohol,  ether  (to  remove  the  fats),  water  (to  remove  the  gelatin),  and  finally 
in  acids  and  alkalies.  This  substance  must  be  previously  prepared  so  that 
the  student  can  test  its  reactions. 

{a. )  It  is  insoluble  in  water,  but  is  soluble  in  strong  caustic  soda. 

{b. )  It  gives  the  xanthoproteic  tests. 

(c. )  It  is  precipitated  from  a  solution  by  tannic  acid. 

5.  V.  Keratin  occurs  in  epitheHal  structures,  e.^.,  surface  layers 
of  the  epidermis,  hairs,  horn,  hoof,  and  nails.  It  is  characterised 
by  the  large  percentage  of  sulphur  it  contains ;  part  of  the  latter 
is  loosely  combined.  It  is  very  insoluble  and  resists  putrefaction 
for  a  long  time.  A  closely-allied  body,  Neuro-Keratin,  is  found  in 
nerve  fibres  and  the  central  nervous  system. 

(a.)  Burn  a  paring  of  horn,  and  note  the  characteristic  smell. 
(b.)  Heat  a  paring  of  nail  or  horn  with  strong  caustic  soda  and 
lead  acetate  =  black  or  brown  colouration,  due  to  lead  sulphide. 
(c.)  Test  for  the  presence  of  sulphur.     (Lesson  I.  2.) 


IIL]  •         THE   CARBOHYDRATES.  15 

LESSON  IIL 

THE    CARBOHYDRATES. 

The  term  Carbohydrate,  first  used  by  C.  Schmidt,  is  apphed  to  a 
large  and  important  group  of  substances,  which  occur  especially  in 
plants,  and  some  of  which,  such  as  starch  and  sugar,  make  up  a 
large  part  of  their  organs ;  while  cellulose,  another  member  of  the 
group,  forms  the  chief  material  from  wliich  many  parts  of  plants 
are  constructed.  Carbohydrates  also  occur,  but  to  a  much  smaller 
extent,  in  animals,  in  which  they  are  chiefly  represented  by 
glycogen  and  some  forms  of  sugar. 

In  elementary  composition  they  are  non-nitrogenous,  and  consist 
of  C,  H,  and  0,  with  the  H  and  0  in  the  same  proportion  as  in 
water,  i.e.^  2  atoms  of  H  to  i  atom  of  0.  As  this  proportion 
obtains  in  many  other  substances  which  certainly  do  not  belong 
to  the  carbohydrate  group,  e.r/.,  acetic  acid  (C2H4O2),  lactic  acid 
(CyHgOg),  the  definition  must  be  somewhat  extended.  The  group 
is  understood  to  include  those  substances  that  do  not  contain  less 
than  6  atoms  of  carbon,  although  many  carbohydrates  contain 
multiples  of  this.  To  every  6  atoms  of  C  there  are  at  least  5 
atoms  of  0,  so  that  on  the  one  hand  acetic  acid  is  excluded,  and 
pyrogalhc  acid  (CgHgOg)  on  the  other. 

They  have  certain  general  characters.  They  are  indifferent 
bodies,  with  a  neutral  reaction,  which  form  only  loose  combina- 
tions with  other  bodies,  specially  with  bases.  Other  general 
characters  they  possess  directly,  e.g.^  dextrose,  or  they  can  be 
readily  converted  into  bodies  wjaich  have  the  following  features  in 
common.  One  or  other  character  may  fail,  but,  as  a  group,  they 
have  the  following : — 

(a.)  The  property  of  reducing  alkalim  metallic  solutions ,  and  of 
being  coloured  yellow  by  alkalies. 

{h.)  They  rotate  the  plane  of  polarised  light. 

(c.)  In  contact  with  yeast  they  spht  up  into  alcohol  and  carbon 
dioxide,  i.e.,  undergo  fermentation,  (Mome  do  not  undergo  fer- 
mentation.) 

{d.)  On  heating  with  HCl  or  HgSO^  they  are  decomposed  with 
the  formation  of  Idvulinic  acid,  humin  substance,  and  formic  acid. 

(e.)  They  give  a  deposit  of  yellow  needles  with  phenyl-hydrazin. 

(/.)  Various  colour  reactions  with  acids  and  aromatic  alcohols. 

(g.)  Some,  e.g.,  cellulose  and  starch,  are  quite  insoluble  in  water, 
while  others  are  very  soluble.  Those  which  are  very  insoluble  in 
water  can  usually  be  rendered  soluble  by  heating  them  with  an 


PRACTICAL   PHYSIOLOGY. 


[IIL 


acid.  This  is  a  process  of  hydrolysis.  They  are  less  soluble  in 
alcohol  the  more  concentrated  it  is.  In  absolute  alcohol  (and 
ether)  almost  all  the  carbohydrates  are  soluble  with  difficulty,  or 
insoluble. 

(h.)  When  strongly  heated  they  are  decomposed,  charred,  and 
yield  a  variety  of  products.  Inosite,  which,  however,  is  not  a  true 
carbohydrate,  alone  undergoes  partial  sublimation  {Tollens). 

Classification  of  some  Carbohydrates : — 


I.  Glucoses  or 

Monosaccharids, 

CeH.^Oe. 

n.  Saccharoses  or 

Disaccharids, 

C12H22O11. 

in.  Amyloses  or 
Polysaccharidfl, 

+  Dextrose. 
-  Laevulose. 
+  Galactose 
Iuosite(?). 

+  Cane-sugar, 
-t-  Lactose. 
+  Maltose. 

+  Starch, 
-f  Dextrin, 
-f  Glycogen. 

Cellulose. 

Gums. 

The  +  and  -  signs  indicate  that,  as  regards  polarised  light,  the  substances 
are  dextro-  and  Isevorotatory  respectively. 


The  amyloses  are  anhydrides  of  the  glucoses  [^^(^6^12^6)  " 
nW^O  =  (C^jH^qO^),,],  Avhile  the  saccharoses  are  condensed  glucoses 
(CgHigOg  +  CjjHigOg  -  H2O  -  CjoHo^Ou)].  The  saccharoses  are 
converted  into  glucoses  on  boiling  with  dilute  sulphuric  acid. 


Emil  Fischer  has  shown  that  the  monosaccharids  are  aldehydes 
or  ketones  of  a  hexatomic  alcohol,  Cj.Hg  (OH)^.  Just  as  aldehyde 
CoH^O  is  formed  by  oxidising  ethylic  alcohol  C2H^0,  so  from 
raannitic  alcohol  the  simplest  carbohydrate  C^-HjoO,,  is  formed. 
When  two  molecules  of  such  monosaccharids  polymerise  with  the 
loss  of  water,  they  form  the  disaccharids,  which  may  spht  up 
again  and  yield  monosaccharids.  When  there  is  further  poly- 
merisation with  loss  of  water  we  get  bodies  with  molecules  of 
larger  size — the  simpler  members  being  dextrins,  the  more  complex 
starch  and  glycogen,  forming  the  group  of  polysaccharids.  These  in 
turn  may  break  down  and  yield  monosaccharid  or  disaccharid 
molecules.  Thus  the  transformation  imdergone  by  carbohydrates 
in  the  organism,  their  conversion  from  one  form  to  another,  are 
rendered  more  easy  of  comprehension. 


III.] 


THE   CARBOHYDRATES. 


17 


1.  I.  Starch  {C^Jl^fi■^),^. — The  n  in  this  case  is  not  less  than  4, 
and  may  be  10  or  20;  indeed,  Brown  and  Heron  suggest  the  for- 
mula ioo(Cj2H2oOjq).  Starch  is  one  of  the  most  widely  distri- 
buted substances  in  plants,  and  it  may  occur  in  all  the  organs  of 
plants,  either  (a.)  as  a  direct  or  indirect  product  of  the  assimila- 
tion of  CO2  in  the  leaves  of  the  plant,  or  (6.)  as  reserve  material 
in  the  roots,  seeds,  or  shoots  for  the  later  periods  of  generation 
or  vegetation. 

Preparation. — Wash  a  potato  tlioroughly,  and  grate  it  on  a  grater  into 
water  in  a  tall  cylindrical  glass.  Allow  the  suspended  particles  to  subside, 
and  after  a  time  rote  the  deposit ;  the  lowest  stratum  consists  of  a  white 
powder  or  starch,  and  above  it  lie  coarser  fragments  of  cellulose  and  other 
matters.  Decant  off  the  supernatant  fluid  which  becomes  brown  on 
standing. 

(a.)  Microscopical  Examinatioa — Examine  the  white  deposit 
of  starch,  noting  that  each  starch-granule  shows  an  eccentric  hilum 


Fig.  3. — Potato  Starch. 

with  concentric  markings  (fig.  3).  Add  a  very  dilute  solution  of 
iodine.  Each  granule  becomes  blue,  while  the  concentric  markings 
become  more  distinct. 

(h.)  Compare  the  microscopical  characters  of  other  varieties  of  starch — e.g., 
rice,  arrowroot,  &c.  Each  granule  consists  of  an  outer  layer  of  cellulose  en- 
closing alternating  layers  of  granulose  and  cellulose,  so  that  they  ])resent  a 
laminated  ajjpearance.  There  are  very  great  varieties  in  the  shape  and  size 
of  starch  grains. 

(c.)  Squeeze  some  dry  starch  i)owder  between  the  thumb  and  forefinger,  and 
note  the  peculiar  crepitation  sound  and  feeling. 

{d.)  Polariscope.  —Examine starch  granules  with  a  polarisation  microsco})e. 
With  crossed  Nicol's,  when  the  field  is  dark,  each  granule  shows  a  dark  cross 
on  a  white  refractive  ground.  They  are  doubly  refractive.  If  a  plate  of  mica 
be  placed  on  the  stage  of  the  microscope  under  the  starch  grains,  the  latter, 
with  polarised  light,  exhibit  interference  colours  (fig.  4). 

2.  Prepare  a  Solution.— Place  i  gram  of  starch  in  a  mortar, 
rub  it  up  with  a  little  cold  water,  and  then  add  50  cc.  of  boiling 
water.     Boil  until  an  opalescent  imperfect  solution  is  obtained. 


1 8  PRACTICAL   PHYSIOLOGY.  [ill 

(a.)  Add  powdered  dry  starch  to  cold  water.  It  is  insoluble. 
Filter,  and  test  the  filtrate  with  iodine.     It  gives  no  blue  colour. 

(h.)  Boil  starch  with  water  =  opalescent  solution,  which  if  strong 
gelatinises  or  sets  on  cooling  =  starch  paste. 

(f.)  Add  a  solution  of  iodine^  =  a  blue  colour,  which  disappears 
on  heating  (the  iodide  of  starch  is  dissociated  by 
heat)  and  reappears  on  cooling — provided  it  has  not 
been  boiled  too  long.  Direct  a  stream  of  cold  water 
upon  the  test-tube  to  cool  it. 

{(1.)  Render  some  of  the  starch  solution  alkaline 
by  adding  caustic  soda  solution.  Add  iodine  solu- 
tion.    ^0  blue  colour  is  obtained. 

(e.)  Acidify  ('/.)  with  dilute  sulphuric  acid,  then 

add  iodine  =  blue  colour  is  obtained. 

Fio.    4.  —  Potato      (/.)  To  anotlier  portion   of  the  solution   add  a 

uie^^  view^'n  ^®"^  drops  of  dilute  cupric  sulphate  and  caustic  soda, 

polarised  light  and  boil  =  no  reaction  (compare  "  Grape-sugar  "). 

Kicoi's,  x^cS^        (O-)    To    another    portion    of    the    solution    add 

Fehhng's  solution,  and  boil  =  no  reaction. 
(h.)  Add  tannic  acid  =  yellowish  precipitate,  which  dissolves  on 
heating. 

3.  Starch  is  a  Colloid. — Place  some  strong  starch  solution  in  a 
dialyser  or  parchment  tube,  and  the  latter  in  distilled  water. 
Allow  it  to  stand  for  some  time,  and  test  the  water  for  starch; 
none  will  be  found. 

(a.)  Does  not  filter. — Two  dry  filter  papers  are  placed  in  two  funnels  about 
5  cm.  in  diameter  and  filled  with  2  per  cent,  solution  of  starch.  Let  one  re- 
main as  a  control,  and  to  the  other  add  any  diastatic  ferment — e.g.,  saliva 
or  liquor  pancreaticus.    The  starch  begins  to  filter,  being  converted  into  sugar. 

4.  II.  Dextrin  (British  Gum)  (CgHjoOg)  is  an  intermediate  pro- 
dact  in  the  hydration  of  starch.  There  are  two  varieties — Erythro- 
dextrin,  which  gives  a  red  colour  with  iodine  ;  and  Ach- 
roodextrin,  which  gives  no  colour  with  iodine  solution  (see 
*'  Saliva  "). 

Examine  its  naked  eye  characters.  It  is  gummy  and  amor- 
phous. Smell  it.  Dissolve  some  dextrin  in  boihng  water,  and 
observe  that  the  solution  is  not  opalescent. 

(a.)  This  proves  its  solubility  in  water. 

(/;.)  Add  iodine  solution  =  reddish-brown  colour,  which  disap- 
pears on  heating  and  returns  on  coohng.  [The  student  ought  to 
use  two  test-tubes,  placing  the  dextrin  solution  in  one,  and  an  equal 

1  Solution  of  Iodine. — Dissolve  2  grams  of  potassic  iodide  in  100  cc.  of 
water,  add  i  gram  of  iodine,  and  shake  well. 


III.]  THE  CARBOHYDRATES.  1 9 

volume  of  water  in  the  other.  Add  to  both  an  eqnal  voUime  of 
sohition  of  iodine,  and  thus  compare  the  difference  in  colour.] 

(c.)  Precipitate  some  of  its  solution  by  adding  alcohol. 

(d.)  Render  some  of  the  dextrin  solution  alkaline  by  adding 
caustic  soda  solution.  No  red-brown  colour  is  obtained  with 
iodine.     Acidify  and  the  reddisli-brown  colour  appears. 

(e.)  It  is  not  precipitated  by  basic  acetate  of  lead  alone  (unlike 
glycogen). 

(/.)  Precipitation  occurs  on  adding  ammonia  and  basic  acetate  of 
lead.  The  ammonia  gives  a  wliite  precipitate  with  lead  acetate 
which  carries  down  dextrin. 

There  are  several  varieties  of  dextrin  : — - 

5.  Prepare  Dextrin  from  Starch. — Make  lo  grams  of  starch  into  a  paste 
with  20  cc.  of  water,  add  30  cc.  of  a  20  per  cent,  solution  of  sulphuric  acid. 
Mix,  and  heat  in  a  water-bath  at  90°  C.  Cool  and  precipitate  the  dextrin  by 
alcohol.     Collect  the  white  deposit,  wash  with  alcohol,  and  dry  it. 

6.  III.  Cellulose  {CqRiqO^)7i  occurs  in  every  tissue  of  the  higher  plants, 
where  it  forms  the  walls  of  cells,  and  the  great  mass  of  the  hard  parts  of 
wood.     Cotton-wool  may  be  used  to  test  its  reactions. 

(a.)  It  is  insoluble  in  water  and  all  the  feebler  solvents. 

{b.)  It  is  soluble  in  Schweitzer's  reagent,  or  a  solution  of  ammonio-cupric 
oxide.  This  is  prepared  by  dissolving  slips  of  copper  in  ammonia  in  an  open 
flask,  or  by  dissolving  precipitated  hydrated  oxide  of  copper  in  20  per  cent, 
ammonia.  The  former  is  prepared  by  precipitating  a  solution  of  sulphate  of 
copper  by  soda  in  the  presence  of  ammonium  chloride, 

(c.)  It  is  soluble  in  concentrated  acids,  and  a  gelatinous  precipitate — called 
amyloid — falls  on  the  addition  of  water.  The  substance  precipitated  gives 
a  blue  colour  with,  iodine.     It  is  also  soluble  in  zinc  chloride. 

{d. )  It  gives  a  blue  colour  with  sulphuric  acid  and  iodine,  but  not  with  the 
latter  alone. 

7  IV.  Glycogen  or  Animal  Starch  n{CQE-^fi^). — Prepare  a 
solution  (see  "Liver").  Note  the  characters  of  the  dry  white 
powder. 

(a.)  Note  that  the  solution  is  opalescent  (unUke  dextrin) ;  add 
iodine  solution  =  red-brown  or  port- wine  red  colour.  As  in  the 
dextrin  test,  use  two  test-tubes,  one  with  water  and  the  other 
with  glycogen,  to  compare  the  difference  in  colour.  The  colour 
disappears  on  heating  and  reappears  on  cooUng.  It  also  dis- 
appears on  the  addition  of  alkalies,  which  break  up  the  feeble 
compound. 

{fi.)  Add  caustic  soda  and  copper  sulphate  solution  =  a  blue 
solution,  boil  =  no  reduction. 

((?.)  Add  basic  lead  acetate  =  a  precipitate  (unUke  dextrin). 

(6?.)  Add  ammonia  and  basic  lead  acetate  =  a  precipitate,  as  in  1  /. 

{^\)  Boil  with  dilute  hydrochloric  acid  =  a  reducing  sugar. 
Neutrahse  the  acid  with  dilute  caustic  soda,  and  test  with  Fehling's 
eoUition  for  a  reducing  sugar,  dextrose  =  a  yellow  precipitate. 


20  PRACTICAL   PHYSIOLOGY.  [ill. 

(/.)  The  solution  is  precipitated  by  alcohol  (2  parts  absolute 
alcohol  to  I  part  of  the  solution). 

{g. )  Heated  witli  potash  or  acetic  acid  the  opalescence  diminishes,  and  the 
solution  becomes  clear. 

{h.)  Its  solutions  (even  .6  per  cent.)  are  powerfully  dextro-rotatory 
(a)D  =  2ii°  {Kiilz). 

8.  V.  Glucose,  Dextrose,  or  Grape-Sugar  {O^^fi^. — In  com- 
merce it  occurs  in  warty  uncrystallised  masses  of  a  yellowish  or 
yellowish-brown  colour.  It  exists  in  fruits,  and  in  small  quantities 
in  the  blood  and  other  fluids  and  organs.  It  is  the  form  of  sugar 
found  in  diabetic  urine.  It  is  readily  soluble  in  water.  Prepare  a 
solution  by  dissolving  a  small  quantity  in  water. 

(a.)  Taste  the  glucose,  and  note 
that  it  is  not  so  sweet  as  cane- 
sugar. 

{h.)  Add  iodine  solution  =  no 
reaction. 

{c.)  Heat  the  solution  with  sul- 
phuric acid  =  darkens  slowly. 

{d.)   Dissolve   some   in   boihng 
absolute  alcohol.    It  crystalUses  in 
transparent  prisms  when  the  alco- 
rm.5.-Dextrose.  hol  COols  (fig    5). 

As  to  the  tests,  they  have  been  classified  as  follows : — 
(A.)  YeUow  Colouration  with  Caustic  Soda  or  Potash. 

(e. )  Moore's  Test. — Heat  the  solution  with  half  its  volume  of  caustic  soda  = 
a  yellow  or  brown  colour  due  to  the  formation  of  glucic  and  melassic  acids. 
The  non-a])j)earance  of  a  yellow  colour  indicates  the  absence  of  dextrose,  but 
tlie  following  substances  also  give  a  yellow  colour  with  NaHO : — All  the 
glucoses,  together  with  milk-sugar  and  lactose. 

(B.)  Tests  Depending  on  Reduction. 

(/:)  Trommer's  Test. — To  the  solution  add  a  few  drops  of  a 
dilute  solution  of  copper  sulphate  (lo  per  cent.),  and  afterwards 
add  caustic  soda  (or  potash)  in  excess,  i  e.,  until  the  precipitate  first 
formed  is  re-dissolved,  and  a  clear  blue  fluid  is  obtained.  The 
hydrated  oxide  of  copper  precipitated  from  the  copper  sulphate  is 
held  in  solution  in  presence  of  dextrose  (and  of  all  the  glucoses). 
Heat  slowly,  turning  the  tube  in  the  flame.  A  httle  below  the 
boihng  point,  if  grape-sugar  be  present  the  blue  colour  disappears, 
and  a  yellow  (cuprous  hydrate)  or  red  (cuprous  oxide)  precipitate  is 
obtained.  Boil  the  upper  surface  of  the  fluid,  and  when  the  yellow 
precipitate  occurs  it  contrasts  sharply  with  the  deep  blue-coloured 
stratum  below.     The  precipitate  is  first  yellow,  then  yellowish-red. 


III.]  THE  CARBOHYDRATES.  21 

and  finally  red.  It  is  better  seen  in  reflected  than  transmitted 
light.  If  no  sugar  be  present,  only  a  black  colour  may  be 
obtained. 

{g.)  Add  Fehling's  solution;  boil  =  a  yellow  or  yellowish-red 
precipitate  of  cuprous  oxide  or  hydrate.  [For  the  method  of 
making  Fehling's  solution,  the  precautions  to  be  observed  in  using 
it,  and  for  some  other  tests  for  glucose,  see  "  Urine."] 

(A.)  Barfoed's  Solution. —To  200  cc.  of  a  solution  of  neutral  acetate  of 
copper,  containing  i  part  of  the  salt  to  15  of  water,  add  5  cc.  of  a  38  per  cent, 
solution  of  acetic  acid.  When  heated  with  dextrose  some  red  cuprous  oxide 
is  precipitated,  while  lactose,  cane-sugar,  maltose,  and  dextrin,  when  they 
are  boiled  with  it  for  a  short  time,  give  no  reaction.  Hence  this  substance 
has  been  used  to  distinguish  dextrose  from  maltose. 

{i. )  Bdttger's  Bismuth  Test.  — Heat  the  fluid  with  caustic  soda  and  a  small 
quantity  of  dry  basic  bismuth  nitrate  =  a  grey  or  black  reduction  product  of 
bismuth  oxide.  For  Nylauder's  modification,  see  "  Urine."  In  all  reactions 
depending  on  reduction,  one  must  recollect  that  some  substances  which  are 
by  no  means  related  to  the  glucoses — e.g.,  uric  acid,  ki-eatinin,  phenyl- 
hydrazine— may  cause  reduction,  and  thus  lead  one  into  error. 

(C.)  other  Reactions. 

(,/.)  Phenyl-Hydrazine  Test. — Two  parts  of  phenyl-hydrazine 
hydrochloride  and  three  of  acetate  of  soda  are  mixed  in  a  test-tube 
with  6-10  cc.  of  the  dextrose 
solution.  Boil  for  20-30 
minutes,  and  then  place  the 
tube  in  cold  water.  If  sugar 
be  present,  a  yellow  crystaUine 
deposit  is  formed,  which, 
microscopically,  consists  of 
yellow  needles  either  detached 
or  arranged  in  rosettes  (fig. 
6).  The  substance  formed  is 
phenyl-glucosazone 
(CjgHgoN^O^),  with  a  melting- 
point  of  204°  C. 

The    arrangement    of    the 
acicular   crystals    I    find   fre- 

,1  .  CI  i.'  Fig.  6.— Crystals  of  Phenyl-Glncosazone,  X  120. 

quently    varies.       bometimes 

they  are  in  rosettes  (see  "  Urine "),  and  at  other  times  more 
feathery.  They  are  soluble  in  alcohol,  and  may  be  recrystallised 
from  it. 

This  is  an  extremely  important  and  reliable  reaction.  The  best 
proportioiis  for  the  ingredients  are  i  part  dextrose,  2  hydrocliloride 
of  phenyl-hydrazine,  3  sodic  acetate,  and  20  water.     The  substance 


:} 


Blue  with  iodine. 


22  PRACTICAL   PHYSIOLOGY.  [lIL 

formed  is  but  slightly  soluble  in  water.     According  to  E.  Fischer, 
the  following  is  the  reaction  which  takes  place  : — 

C,Hi  A  +  2CAIT,H3  =  C,8H,,N,0,  +  2H,0  +  2H. 

Phenyl-glucosazone. 

(k.)  Molisch's  Test. — (i.)  To  the  solution  add  a  drop  or  two  of  a  15-  20  per 
cent,  alcoholic  solution  of  a-naphthol,  and  1-2  vols,  of  concentrated  sulphuric 
acid.  The  colour  which  first  appears  is  violet ;  water  causes  a  bluish-violet 
deposit,  (ii.)  If,  instead  of  the  naphthol,  an  alcoholic  solution  of  thymol  be 
used,  a  red  colour  is  obtained.  Seegen,  however,  points  out  that  this  re- 
action can  be  obtained  with  other  substances,  e.g.,  albumin,  which,  however, 
is  denied  by  Molisch.     It  is  not  a  reliable  test. 

9.  Conversion  of  Starch  into  Glucose. — Boil  starch  solution 
with  a  few  drops  of  20  per  cent,  sulphuric  acid,  until  the  fluid 
becomes  clear.  After  neutralising  with  sodium  carbonate,  test  tho 
fluid  for  glucose  by  the  tests  (6.)  or  (c). 

A  large  number  of  intermediate  products,  however,  are  formed. 
They  are  as  follows  (see  also  '*  SaHva  ")  : — 

Starch 

Soluble  starch  (amidulin  or  amylodextrin) 

V  aneties  \  Ej.ythrodextrin          ....  Iodine  gives  violet  and  red. 

Dextrin    I  ^chroodextrin No  reaction  with  iodine. 

,,  ,^  r  Fehling's  solution  reduced. 

^al^ose i  Barfoed's  not. 

Dextrose Both  are  reduced. 

Estimation  of  Glucose  (see  "  Urine  "). 

10.  VI.  Maltose  (Ci2H220ii)- — I^  forms  a  fine  white  warty 
mass  of  needles,  and  is  the  chief  sugar  formed  by  the  action  of 
diastatic  ferments  on  starch.  See  "SaUva,"  and  "Pancreatic 
Juice." 

(a.)  Mix  I  gram  of  ground  malt  with  ten  times  its  volume  of 
water,  and  keep  it  at  60°  C.  for  half  an  hour.  Boil  and  filter ;  the 
filtrate  contains  maltose  and  dextrin. 

(h.)  Test  for  a  reducing  sugar  with  Fehling's  solution  or  other 
suitable  test.     (See  also  "  Sahvary  digestion.") 

{c.)  Boiled  for  ij  hours  with  the  phenyl-hydrazine  test  it  yields 
phenyl-maltosazone  (C24H32N4O9).  It  crystalUses  in  yellow 
needles  (fig.  8). 

(d.)  It  is  soluble  in  water  and  alcohol.  Examine  its  crystals 
(fig.  7).  Its  specific  rotatory  power  is  +150°,  i.e.,  it  is  greater 
than  that  of  dextrose,  but  its  reducing  power  (on  Fehling's  solution) 
is  only  two-thirds  of  that  of  dextrose. 

(c.)  With  Barfoed's  reagent,  i.e.,  when  boiled  with  half  its  volume  of  copper 
acetate,  acidulated  with  acetic  acid  =  no  reduction.  In  this  respect,  and  in 
some  others,  it  differs  from  dextrose. 


III.] 


THE   CARBOHYDRATES. 


23 


(/.)  Preparation  of  Maltose. — Take  i  part  of  potato-starch  and  make  it 
into  a  paste  with  10  of  water.  Digest  the  paste  with  a  filtered  extract  of 
low-dried  malt  (200  grams  to  i  litre  of  water)  for  an  hour  at  57-60'  C,  filter, 
evaporate,  precipitate  the  dextrin  with  alcohol,  concentrate  the  filtrate  to  a 
syrup,  and  allow  the  maltose  to  crystallise. 

11.  Estimation  of  Maltose.— (i.)  Determine  its  reducing  power 
on  10  cc.  of  Feliling's  solution  (see  "Urine"). 

(ii.)  Convert  it  into  dextrose  by  boiling  (J  an  hour)  50  cc.  of  tlie 
solution  with  i  cc.  of  H^SO^.  Cool  and  bring  the  solution  to  the 
original  volume  (50  cc.)  by  adding  water.  Again  determine  its 
reducing  power  by  Fehhng's  solution.  If  a:  =  cc.  of  maltose 
solution  necessary  to  reduce  10  cc.  of  Feliling's  solution,  then  as 


Flo.  7.— Crystals  of  Maltose. 


Fig.  8.— Crystals  of  Phenyl- Maltosazone,  x  120. 


the  respective  reducing  powers  of  glucose  and  maltose  are  as  2  :  3 

2X 

—  =  cc.  of  dextrose  solution  necessary  for  the  same  purpose.     As 

10  cc.  of  Fehling  correspond  to  o  05  grms.  dextrose,  the  strength 
of  the  maltose  solution  can  easily  be  calculated. 

12.  VII.  Lactose  (Milk-Sugar),  Ci.,H220ii  +  H20  (see  "xAlilk"). 

(a.)  Note  its  whiteness  and  hardness.  It  is  not  so  sweet  as 
cane-sugar.     Microscopically  it  occurs  in  rhombic  prisms  (fig  9). 

(/>.)  It  is  less  soluble  in  water  than  cane-  or  grape-sugar,  and 
insoluble  in  alcohol. 

{('.)  Heat  its  solution  carefully  with  sulphuric  acid  =  chars 
slowly. 

{d}j  Add  excess  of  caustic  soda,  and  a  few  drops  of  copper 
sulphate  solution,  and  heat  =  yellow  or  red  precipitate  (like 
dextrose). 

(e.)  Test  with  Fehling's  solution  =  reduction  like  dextrose,  but  its 
reducing  power  is  not  so  great  as  dextrose.  It  requires  10  parts  of 
lactose  to  reduce  the  amount  of  Fehling's  solution  that  will  be  re- 
duced by  7  of  dextrose. 


24 


PRACTICAL  PHYSIOLOGY. 


[IIL 


(/".)  It   is   precipitated  from   its   saturated    watery  solution  by 
absolute  alcohol. 


oo 


'^O 


FlO.  9.— Crystals  of  Lactose.  FlO.  10.— Crystals  of  Phenyl-lactosazone,  X  12c 

{g.)  The  phenyl-hydrazine  test  (fig.  10),  it  yields  phenyl-lactosa 
zone  (C24H32N4O9). 

13.  Preparation  of  Lactose  (C,2H.>20„+HoO).— Acidulate  milk  with  acetit 
acid  =  precipitate  of  caseinogen  and  fat ;  filter;  boil  filtrate  to  precipitate  albumin, 
and  filter  again  ;  evaporate  the  filtrate  to  small  bulk  ;  set  aside  to  crystallise. 

Milk-sugar  is  soluble  in  6  parts  of  cold  and  2^  parts  of  hot  wat^r,  but  not  in 
alcohol. 


14.  VIII.  Cane-Sugax  {G^^^^fi^^). 

{a.)  Observe  its  crystalline  form 

D(fig.  11)  and  sweet  taste. 
{h.)  Its  solutions  do  not  reduce 
^         4  FehUng's    solution    (many   of  the 

^^^^^y  commercial  sugars,   however,  con- 

K  yi ^v     tain  sufficient  reducing  sugar  to  do 

(1     I 1  A rZW  *'"')• 

XJ      I J     h '^1  I        {(-.)  Trommer's  test :  add  excess 

^       ^         *  4'!/L.— -- - — l^     of  caustic  soda,  and  a  drop  of  solu- 
tion of  copper  sulphate  (it  gives  a 
clear  blue  fluid),  and  heat.     With 
a  pure  sugar  there  should  be  no  reduction. 

{(1.)  Pour  strong  sulphuric  acid  on  cane-sugar  in  a  beaker,  add 
a  few  drops  of  water ;  the  whole  mass  is  quickly  charred, 
(e.)  Heat  the  solution  with  caustic  soda  =  it  darkens  slowly. 
(/.)  It  is  practically  insoluble  in  absolute  alcohol,  but  its  solu- 
bihty  greatly  increases  with  the  dilution  of  tlie  alcohol. 

((J.)  Inversion  of  Cane-Sugar. — Boil  a  strong  solution  of  aane- 
sugar  in  a  flask  with  one-tenth  of  its  volume  of  strong  hydro- 
chloric acid.     After  prolonged  boiling  the  cane-sugar  is  "inverted," 


Fia.  II.— Crystals  of  Cane-sugar. 


III.]  THE   CARBOHYDRATES.  2 5 

and  the  solution  contains  a  mixture  of   dextrose   and   laevulose. 
Test  its  reducing  power  with  Fehling's  solution. 

Cane-Sugar.         Water.  Glucose.  Laeyulosa 

^12^22^11   +   ^2^   =  ^6^12^6  +  ^0^12^6' 

(h.)  Estimation  of  Cane-Sugar. — Take  lo  cc.  of  the  cane-sugar 
solution,  add  i  cc.  of  a  25  per  cent,  solution  of  H2SO4.  Boil  for 
half  an  hour,  and  then  make  up  bulk  of  fluid  to  its  original 
volume.  The  cane-sugar  is  converted  into  a  reducing  sugar, 
dextrose.  Place  tlie  fluid  in  a  burette,  and  estimate  its  reducing 
power  on  Fehling's  solution  (see  "Urine.")  95  parts  of  glucose 
correspond  to  100  parts  of  cane-sugar. 

15.  Invert  Sugar — a  mixture  of  grape-sugar  and  fruit-sugar— is  widely 
distributed  throughout  the  vegetable  kingdom,  and  is  so  called  because  it 
rotates  the  plane  of  polarised  light  to  the  left,  the  specific  rotatory  power  of 
the  laevulose  being  greater  than  that  of  dextrose  at  ordinary  temperatures. 

16.  Conversion  of  Starch  into  a  Eeducing  Sugar. — Place  50 
cc.  of  starch  solution  in  a  flask  on  wire  gauze  over  a  Bunsen  burner, 
add  one  drop  of  strong  sulphuric  acid,  and  boil  from  five  to  ten 
minutes,  observing  the  spluttering  that  occurs,  the  liquid  meantime 
becoming  clear  and  limpid. 

{a.)  Test  a  portion  of  the  liquid  for  glucose,  taking  care  that 
sufficient  alkali  is  added  to  neutralise  the  surplus  acid. 

(h.)  Add  iodine  =  blue  colour,  showing  that  some  soluble  starch 
(amidulin)  remains  unconverted  into  a  reducing  sugar. 


ADDITIONAL  EXERCISES. 
Polarimeters, 

17.  Circumpolarisation.— Certain  substances  when  dissolved  possess  the 
power  of  rotating  the  plane  of  polarised  light,  e.g.,  the  proteids,  sugars,  &c. 
The  extent  of  the  rotation  depends  on  the.  amount  of  the  active  substance 
in  solution.  The  direction  of  rotation— ?.c.,  to  the  right  or  the  left —is 
constant  for  each  active  substance.  Of  course,  light  of  the  same  wave- 
length must  be  used.  The  light  obtained  from  the  volatilisation  of  common 
salt  is  used. 

The  term  "specific  rotatory  power,"  or  "specific  rotation"  of  a  substance, 
is  used  to  indicate  the  amount  of  rotation  expressed  in  degrees  of  the  plane  of 
polarised  light  which  is  produced  by  i  gram  of  the  substance  dissolved  in 
I  cc.  of  liquid,  when  examined  in  a  layer  i  decimetre  thick. 

Those  substances  which  cause  specific  rotation  are  spoken  of  as  '  *  optically 
active  ;"  those  which  do  not,  as  '*  inactive." 


26 


PhACTICAL   PHYSIOLOGY. 


[III. 


If  a  =  the  observed  rotation  ; 

"p  =  the  weight  in  grams  of  the  active  substance  contained  in  i  cc  of 

liquid  ; 
Z  =  the  length  of  the  tube  in  decimetres  ; 
(a)D  =  the  specific   rotation   for  light    corresponding  to  the  light  of  a 
sodium  flame  ; 
then 

The  sign  +  or  -  indicates  that  the  substance  is  dextro-  or  laevo-rotatory. 
Various  instruments  are  employed.     Use 


Laurent's  Polarimeter.  —  This  instrument  is  a  so-called 
polarimeter,"  and  must  be  used  in  a  dark  room  (fig.  12). 


half-shadow 


Fig  12.— Laurent's  Half- Shadow  Polarimeter. 

18.  Determination  of  the  Specific  Rotatory  Power  of  Dextrose. 

(a.)  Fill  one  of  the  decimetre  tubes  with  distilled  water,  taking  care  that 


\ 


HI.] 


THE   CARBOHYDRATES. 


27 


no  air-bubbles  get  in.  Slip  on  the  glass  disc  horizontally,  and  screw  tlie 
brass  cap  on  the  tube,  taking  care  not  to  do  so  too  tightly.  Place  the  tube 
in  the  instrument,  so  that  it  lies  in  the  course  of  the  rays  of  polarised  light. 

(b.)  Place  some  common  salt  (or  fused  common  salt  and  soda  carbonate)  in 
the  platinum  spoon  (A),  and  light  the  Bunsen's  lamp,  so  that  the  soda  is 
volatilised.  If  a  platinum  spoon  is  not  available,  tie  several  platinum  wires 
together,  dip  them  into  slightly  moistened  common  salt,  and  fix  them  in 
a  suitable  holder,  so  that  the  salt  is  volatilised  in  the  outer  part  of  the  flame. 
In  the  newer  form  of  the  instrument  supplied  by  Laurent,  there  are  two 
Bunsen-burners,  placed  the  one  behind  the  other,  which  give  very  much 
more  light.     Every  part  of  the  apparatus  must  be  scrupulously  clean. 


Wild's  Polaristrobometer. 


(c.)  Bring  tlie  zero  of  the  vernier  to  coincide  with  that  of  the  scale.  On 
looking  through  the  eye-piece  (0),  and  focussing  the  vertical  line  dividing 
the  field  vertically  into  two  halves,  the  two  halves  of  the  field  should  have 
the  same  intensity  when  the  scale  reads  zero.  If  this  is  not  the  case,  then 
adjust  the  prisms  until  it  is  so,  by  means  of  the  milled  head  placed  for  thai 
purpose  behind  the  index  dial  and  above  the  telescope  tube.  It  is  well  to 
work  with  the  field  not  too  brightly  illuminated. 

(d.)  Remove  the  water- tube,  ana  substitute  for  it  a  similar  tube  containing 
the  solution  of  the  substance  to  be  examined— in  this  case  a  perfectly  clear 
solution  of  pure  dextrose.  Place  the  tube  in  position,  and  proceed  as  before. 
The  two  halves  of  the  field  are  now  of  unequal  intensity.  Rotate  the  eye- 
piece until  equality  is  obtained. 

{e.)  Repeat  the  process  several  times,  and  take  the  mean  of  the  readings. 
The  difference  between  this  reading  and  the  first  at  (c),  when  the  tuba 


28 


PRACTICAL   PHYSIOLOGY. 


[ill. 


was  filled  with  distilled  water  —  i.e.,  zero  =  is  the  rotation  due  to  the 
dextrose  =  a. 

(/".)  Place  lo  cc.  of  the  solution  of  dextrose  in  a  weighed  capsule,  evaporate 
to  dryness  over  a  water-bath,  let  the  capsule  cool  in  a  desiccator,  and  weigh 
again.  The  increase  in  weight  gives  the  amount  of  dextrose  in  lo  cc.  ;  so  that 
the  amount  in  i  cc.  is  got  at  once  =  ;>. 

{g. )  Calculate  the  specific  rotatory  power  by  the  above  formula.     It  is  about 

+  53". 

For  practice,  begin  with  a  solution  of  dextrose  containing  1 1  grams  per  loo  cc. 
of  water.     Make  several  readings  of  the  amount  of  rotation,  and  take  the  mean. 

Example. — In  this  case,  the  mean  of  the  readings  was  ii.6°. 


(a)D  = 


^11.6" 

.II  X2 


=  53°. 


Repeat  the  process  with  a  4  and  2  per  cent,  solution.  It  is  necessary  to  be 
able  to  read  to  two  minutes,  but  considerable  practice  is  required  to  enable  one 
to  detect  when  the  two  halves  of  the  field  have  exactly  the  same  intensity. 

Test  the  rotatory  power  of  corresponding  solutions  of  cane-sugar,  and  any 
other  sugar  you  please. 

Test  also  the  rotatory  power  of  a  proteid  solution. 

The  following  indicate  the  S.R.  for  yellow  light:  — 

Proteids. — Egg-albumin  -  35.5° ;  serum-albumin  -  56° ;  syntonin 
-72°;  alkali-albumin  prepared  from  serum-albumin  -  86°,  when 
prepared  from  egg-albumin  -  47°. 

Carbohydrates. — Glucose  +  56° ;  maltose  +150°;  lactose  +  52.5°. 

N.B. — A  complication  sometimes  arises  in  connection  with  carbohydrates, 
as  the  S.K.  is  sometimes  much  altered  by  the  temperature  ;  thus  the  S.R.  of 
laevulose,  when  heated  from  20-90°  C. ,  falls  in  the  pro- 
portion of  3  : 2.  It  is  best,  therefore,  to  work  at  a 
constant  temperature,  say  20°  C.  Again,  some  solutions 
have  not  the  same  S.R.  when  they  are  first  dissolved 
that  they  have  twenty-four  hours  afterwards.  This  is 
•  ^N^^^N>— ^mM  called  birotation,  and  it  is  therefore  well  to  use  the 
solution  twenty-four  hours  after  it  is  made. 

Wild's  Polaristrobometer.  —  Between  the 
polariser  (which  can  be  rotated)  and  analyser 
of  this  instrument  is  placed  a  Savart's  polari- 
scope,  which  produces  in  the  field  a  number  of 
parallel  dark  interference-lines. 

A  framework  H,  which  can  be  moved  on  a  brass 
support  F,  carries  the  analyser  and  polariser.  The 
light  from  a  soda-flame  enters  at  D,  traverses  a  Nicol's 
prism  which  is  fixed  to  and  moves  with  the  graduated 
index  K.  The  polarised  rays  then  traverse  the  fluid 
contained  in  a  tube  placed  in  L,  and  reach  the  fixed 
ocular  parts  containing  the  so-called  polariscope.  The 
latter  is  composed  of  two  prisms,  which  give  rise  to  the  interference-lines,  which 
are  viewed  by  means  of  a  lens  of  short  focus.  Between  M  and  N  is  a  diaphragm 
with  X -shaped  cross  lines.     Beyond  M,  which  is  designed  to  protect  the  eye 


FlO.  14. — a.  Interference 
lines  seen  with  fig.  13. 


J 


tV.]  THE   CARBOHYDRATES.  29 

of  tlie  observer  from  extraneous  light,  is  the  other  Nicol's  prism.  The 
polariser  can  be  rotated  by  means  of  G.  In  order  to  read  oil"  tlie  scale,  there 
is  a  telescope  B.  In  S  is  a  small  mirror  which  reHects  the  flame  of  a 
movable  source  of  light  upon  the  nonius.  Usually  the  instrument  is  made 
for  a  column  of  Huid  220  mm.  long. 

(i.)  Light  the  movable  gas-flame  opposite  Q.  Estimate  the  zero-point  of 
the  instrument  by  placing  an  empty  tube  in  the  instrument,  and  focus  until 
the  lines  of  the  cross  are  sharply  seen.  Rotate  the  polariser  by  means  of  0 
until  the  illuminated  field  is  seen  to  be  traversed  by  dark  interference-lines 
(fig.  14,  a).  On  rotating  still  further,  the  lines  become  paler,  until  ultimately 
a  clear  space  without  lines  occupies  the  field.  Try  to  get  this  in  the  middle 
of  the  field  as  in  fig.  14,  b, 

(2.)  Replace  the  empty  tube  with  the  fluid  to  be  investigated,  when  the 
interference-lines  reappear.  Suppose  the  substance  is  dextro-rotatory,  then 
rotate  the  Nicol  to  the  left  until  the  lines  disappear  ;  but  from  the  arrange- 
ment of  the  apparatus,  the  milled- head  C  is  moved  in  the  same  direction  as 
the  direction  of  rotation  of  the  substance.  It  is  well  to  make  readings  in  all 
four  quadrants  of  the  instrument.  It  is  best  to  use  the  instrument  in  a  dark 
room. 


LESSON  IV. 

FATS— BONE— EXERCISES    ON    THE    FOREGOING. 

NEUTRAL  FATS. 

The  neutral  fats  of  the  adipose  tissue  of  the  body  generally  con- 
sist of  a  mixture  of  the  neutral  fats  stearin,  palmitin,  and  olein, 
the  former  two  being  solid  at  ordinary  temperatures,  while  olein 
is  iluid,  and  keeps  the  other  two  in  solution  at  the  temperature 
of  the  body. 

Neutral  fats  are  derivatives  of  the  triatomic  alcohol  glycerin, 


'3H5  I  o 


and  are  glycerides  or  compound  ethers  of  palmitin,  stearin,  and 
olein,  in  which  three  of  the  hydrogen  atoms  of  the  glycerin  are 
replaced  by  as  many  equivalents  of  the  acid  radical. 

I.  Reactions. 

(a.)  They  are  lighter  than  water;  sp.  gr.  .91-94. 

(h.)  Use  almond  or  olive  oil  or  lard,  and  observe  that  fat  is 
soluble  in  ether,  chloroform,  and  hot  alcohol,  but  uisoluhle  in 
water. 

(c  ^  Dissolve   a  little   fat  in  3  cc.  ether.      Let  a  drop  of  the 


30 


PRACTICAL   PHYSIOLOGY. 


[IV. 


ethereal  solution  fall  on  paper,  e.rj.^  a  cigarette  paper  =  a  greasy 
stain  on  the  paper,  which  does  not  disappear  with  strong  heat. 

{d.)  To  ohve  oil  or  suet  add  caustic  potash,  and  boil.  Stearin  is 
present  in  the  suet  and  is  glycerin-stearate,  while  olein  in  olive 
oil  is  glycerin-oleate.  When  stearin  is  boiled  with  a  caustic 
alkali,  e.g.^  potash,  a  potassic  stearate  or  soap  is  formed,  and 
glycerin  is  set  free.     This  is  the  process  of  saponification. 


Tri-Stearin 
3C18H35O 


'^  lo 


Potash.         Potassic  Stearate  ^Soap).         Glycerin. 
,3|}0  =  3C:sH.0j03  +  C3H.|03 


(?.)  Heat  lard  and  caustic  soda  solution  in  a  capsule  to  form  a  soap;  decom- 
pose the  latter  by  heating  it  with  dilute  sulphuric  acid,  and  observe  the 
liberated  fatty  acids  floating  on  the  top. 

(/.)  Proceed  as  in  ('/.),  and  add  to  the  soap  solution  crystals  of  sodium 
chloride  until  the  soaps  separate. 

(^.)  Shake  oil  containing  a  fatty  acid,  e.g.^  De  Jongli's  cod-liver 
oil,  with  a  few  drops  of  a  dilute  solution  of  sodic  carbonate.  The 
whole  mass  becomes  wliite  =  emulsion.  Examine  it  microscopi- 
cally, and  compare  it  with  milk,  which  is  a  typical  emulsion. 

In  an  emulsion  the  particles  of  the  oil  are  broken  up  into 
innimierable  finer  particles,  which  remain  discrete,  i.e.,  do  not  run 
together  again. 

(/i.)  Shake  up  olive  oil  with  a  solution  of  albumin  in  a  test- 
tube  =  an  emulsion.     Examine  it  microscopically. 

(/.)  Gad's  Emulsion  Experiment. — Place  in  a  watch-glass  a  solution  of 
sodic  carbonate  (.25  per  cent.),  and  on  the  latter  place  a  drop  of  rancid  oil. 

The  drop  comes  to  rest,  but  soon  the  oil 
drop  shows  a  wliite  rim,  and  at  the  same 
time  a  white  milky  opacity  extends  over 
the  soda  solution.  With  the  microscope, 
note  the  lively  movement  in  the  neighbour- 
hood of  the  fat-droplet,  due  to  the  separa- 
tion of  excessively  minute  particles  of  oil. 
The  white  fluid  is  a  fine  and  uniform 
emulsion  (fig.  15).  This  experiment  has 
an  important  bearing  on  the  formation  of 
an  emulsion  in  the  intestine  in  connection 
with  the  i^ancreatic  digestion  of  fats. 

(j.)  Ranvier's  Emulsion  Experiment. — 
Ranvier  has  shown  that  if  a  drop  of  lymph 
taken  from  the  peritoneal  cavity  of  a  frog 
be  mixed  on  a  microscopical  slide  with  a 
Fro.  i5.-Gad'3  Experiment.  drop  of  olive   oil,    on   examining   with   a 

microscope  where  the  two  fluids  come  into 
contact,  one  sees  emulsification  going  on  before  one's  eyes,  with  the  forma- 
tion of  fine  particles  of  oil  like  the  molecular  basis  of  chyle  {Comptes  reiidics, 
1894). 


IV.]  f^ATS — BONE.  31 

(k.)  Heat  in  a  porcelain  capsule  for  an  hour  or  more  some  lard  mixed  with 
plumbic  oxide  and  a  little  water.  The  fat  is  split  up,  yielding  glycerin  and 
a  lead -soap. 

BONE. 

2.  (A.)  Organic  Basis  of  Bone. 

(a.)  Decalcify  Bone. — Place  a  small  thin  dry  bone  in  dilute 
hydrochloric  acid  (1:8)  for  a  few  days.  Its  mineral  matter  is 
dissolved  out,  and  the  bone,  although  retaining  its  original  form, 
loses  its  rigidity,  and  becomes  pliable,  and  so  soft  as  to  be  capable 
of  being  cut  with  a  knife.  What  remains  is  the  organic  matrix  or 
ossein.     Keep  the  solution  obtained. 

{!>.)  Wash  the  decalcified  bone  thoroughly  with  water,  in  which  it  is  in- 
soluble ;  place  it  in  a  solution  of  sodium  carbonate  and  wash  again.  Boil  it 
in  water,  and  from  it  gelatin  will  be  obtained.  Neutralise  with  sodium 
carbonate.  The  solution  gelatinises.  Test  the  solution  for  gelatin  (Lesson 
II.  1). 

(c. )  Decalcify  a  small  portion  of  a  dry  bone  with  picric  acid. 

(B.)  Mineral  Matter  in  Bone. 

(a.)  Examine  a  piece  of  bone  which  has  been  incinerated  in  a 
clear  fire.  At  first  the  bone  becomes  black  from  the  carbon  of  its 
organic  matter,  but  ultimately  it  becomes  white.  What  remains 
is  calcined  bone,  having  the  form  of  the  original  bone,  but  now  it 
is  quite  brittle.     Powder  some  of  the  white  bone-ash. 

(b.)  Dissolve  a  little  of  the  powdered  bone-ash  in  hydrochloric 
acid,  observing  that  bubbles  of  gas  (COg)  are  given  off,  indicating 
the  presence  of  a  carbonate;  dilute  the  solution,  add  excess  of 
ammonia  =  a  white  precipitate  of  phosphate  of  lime  and  phosphate 
of  magnesia. 

(<".)  Filter,  and  to  the  filtrate  add  ammonium  oxalate  =  a  white 
precipitate  of  oxalate  of  lime,  showing  that  there  is  lime  present, 
but  not  as  a  phosphate. 

('/.)  To  the  solution  of  mineral  matters  2  (A.)  {a.)  add  acetate 
of  soda  until  there  is  free  acetic  acid  present,  recognised  by  the 
smell ;  then  add  ammonium  oxalate  =  a  copious  white  precipitate 
of  lime  salts. 

(e.)  Use  solution  of  mineral  matters  obtained  in  2  (A.)  (a.)  Render  a  part 
alkaline  with  NH4H0  =  copious  precipitate,  redissolve  this  in  acetic  acid, 
wliich  dissolves  all  except  a  small  flocculent  residue  of  phosphate  of  iron 
(perhaps  in  part  derived  from  the  blood  of  bone).  Filter  ;  use  a  small  part  to 
test  for  phosphoric  acid  and  the  rest  for  calcium  and  magnesium  (Filtrate  A.). 

(i.)  The  undissolved  flocculent  precipitate  is  waslied  and  dissolved  in  a  few 
cc.  dilute  HCl.  and  the  presence  of  iroji  oxide  proved  by  adding  ferrocyanide  of 
potassium  ( =  blue),  and  that  of  phosplwfic  acui  by  molybdate  of  ammonium 
(see  "  Urine"). 


32  PRACTICAL   PHYSIOLOGY.  [iV. 

(ii.)  Witli  the  filtrate  A.  test  for  phosjihoric  acid  by  uranium  acetate  = 
yellowish -white  precipitate  of -uranium  phosphate  (Ui'02)HP04. 

(iii.)  Calciiun,  by  adding  ammonium  oxalate  Ca.2C.2O4  +  H.^O.  Filter,  and 
when  the  filtrate  is  clear  and  gives  no  longer  a  precipitate  with  ammonium 
oxalate,  make  it  alkaline  with  NH4HO  =  after  a  time  crystalline  precipitate  of 
ammonio  -  magnesium  phosphate  MgNH4P04  +  6H2O,  showing  presence  of 
magnesium. 


3.  examinatio:n"  of  a  solution  for  proteids 
and  carbohydrates. 

I.  Physical  Characters. 

(a.)  Note  colour  and  transparency.  Glycogen  solution  is 
opalescent,  starch  and  some  proteid  solutions  less  so. 

(h.)  Taste.  Salt  solution  may  contain  globulin.  A  sweet  taste 
indicates  a  sugar. 

(c.)  Smell.  The  beef- tea  odour  of  albumose  and  peptone  solution, 
and  the  smell  of  British  gum  are  characteristic. 

(d.)  Other  characters.  Thus  a  persistent  froth  is  suggestive  of 
an  albuminous  solution. 

II.  Test  for  proteids  by  xanthoproteic  and  Millon's  tests.  If 
present : 

1.  Test  reaction  to  litmus  paper.  If  acid  or  alkaline,  test  for 
acid-  or  alkaH-albumin,  and  if  either  is  present,  neutralise,  and 
filter  off  precipitate.  Test  filtrate  for  proteoses  and  peptones  as  in 
4  and  5. 

2.  If  original  solution  is  neutral,  acidulate  faintly,  and  boil.  A 
coagulum  may  consist  of  native  albumin,  or  globulin,  or  both.  Filter; 
and  test  filtrate  for  proteoses  and  peptones  as  in  4  and  5. 

3.  Distinguish  between  albumin  and  globulin  by  (a.)  dropping 
solution  into  water,  precipitate  indicates  globulin,  {b.)  saturating 
solution  with  INIgSO^,  precipitate  =  globulin,  but  may  also  contain 
proto-  and  hetero-albumose.  If  precipitate  obtained  by  (b),  filter 
and  boil  filtrate,  coagulum  =  native-albumin.  Distinguish  between 
egg-  and  serum-albumin  by  eth.er  test. 

4.  Add  excess  of  NaHO,  then,  drop  by  drop,  very  dilute  CuSO^, 
pink  colour  indicates  proteoses,  or  peptones,  or  both. 

5.  Separate  proteoses  from  peptones  by  saturating  solution  with 
AmgSO^.     Precipitate  =  proteoses.     Filter ;  and  to  filtrate  add  large 


v.]  THE  BLOOD.  33 

excess  of  syrupy  solution  of  NaHO,  then  dilute  CuSO^.  Pink 
colour  indicates  peptones. 

[6.  Gelatin  (albuminoid),  gives  Xanthoproteic  and  Millon's  re- 
actions, gives  a  violet  colour  with  ISTaHO  and  CuSO^,  is  not  coagu- 
lated by  boiling,  and  is  not  precipitated  by  acetic  acid  and  potas- 
sium ferrocyanide.] 

III.  Test  for  Carbohydrates.  First  remove  derived  albumins 
by  neutralising  and  filtering,  and  native  albumin  and  globulin  by 
boiling  and  filtering. 

1.  Acidulate  if  necessary  and  add  iodine. 

(a.)  Blue  colour,  disappearing  on  heating  and  returning  on  cool- 
ing, indicates  starch. 

{b.)  MaJiogany-hroion  colour,  disappearing  on  heating  and  return- 
ing on  cooling,  indicates  glycogen  or  dextrin.  Add  basic  lead 
acetate,  precipitate  (if  proteids  are  absent)  =  glycogen. 

2.  Test  for  reducing  sugar  by  Trommer's  test.  If  present,  dis- 
tinguish glucose,  maltose,  and  lactose,  by  the  phenyl-hydrazine  test 
(p.   2l). 

3.  If  no  starch,  dextrin,  glycogen  or  reducing  sugar,  examine  for 
cane-sugar  by  inversion  test. 


LESSON  V. 
THE  BLOOD— COAGULATION-  ITS  PROTEIDS. 

1.  Reaction. — Constrict  the  base  of  one  finger  by  means  of  a 
handkerchief.  When  the  finger  is  congested,  with  a  clean  sewing 
needle  prick  the  skin  at  the  root  of  the  nail.  Touch  the  blood 
with  a  strip  of  dry,  smooth,  neutral  litmus  paper,  highly  glazed  to 
prevent  the  red  corpuscles  from  penetrating  into  the  test  paper. 
Allow  the  blood  to  remain  on  it  for  a  short  time  ;  then  wash  it  off 
with  a  stream  of  distilled  water,  when  a  blue  spot  upon  a  red  or 
violet  ground  will  be  seen,  indicating  its  all-aline  reaction,  due 
chiefly  to  sodium  phosphate  (Na^HPO^)  and  sodium  carbonate. 

2.  Blood  is  Opaque. 

{a.)  Place  a  thin  layer  of  defibrinated  blood  on  a  glass  slide  ;  try 
to  read  printed  matter  through  it.     This  cannot  be  done. 

3.  To  make  Blood  Transparent  or  Laky. — Place  10  cc.  of  de- 
fibrinated blood  in  each  of  three  test-tubes,  labelled  A,  B,  and  C. 
A  is  for  comparison. 

(a.)  To  B  add  5  volumes  of  water,  and  warm  slightly,  noting 
the  change  of  colour  by  reflected  and  transmitted  light.     By  re- 

o 


34  PRACTICAL  PHYSIOLOGY.  [V. 

fleeted  light,  it  is  much  darker,  it  looks  almost  black — but  by 
transmitted  light  it  is  transparent.  Test  this  by  looking  as  in  2 
(a.)  at  printed  matter. 

(h.)  To  C  add  a  watery  solution  of  taurocholate  of  soda.  Test 
the  transparency  of  the  mixture.  In  2,  the  haemoglobin  is  still 
witliin  the  blood  corpuscles.  In  the  others — 3  (r/.),  {b.) — it  is 
dissolved  out,  and  in  solution. 

4.  Specific  Gravity  of  Blood. — {a.)  Make  a  number  of  solutions  of  sulphate 
of  soda,  varying  in  sp.  gr.  from  i. 050-1. 075.  At  least  twenty  sej)arate  solu- 
tions are  required,  each  with  a  definite  sp.  gr.  Pour  a  small  quantity  of  the 
solutions  into  small  glass  thimbles.  A  thin  glass  tube  is  drawn  out  in  a  gas- 
flame  to  form  a  capillary  tube,  which  is  bent  at  a  right  angle,  and  closed 
above  with  a  small  caoutchouc  cap.  A  drop  of  blood  is  obtained  from  a 
finger,  and  by  pressing  lightly  on  the  caoutchouc  cap  a  quantity  of  the 
freshly-shed  blood  is  drawn  up  into  the  capillary  part  of  the  tube.  The  tip  of 
the  fine  capillary  tube  is  at  once  immersed  in  one  of  the  solutions  of  sodic  sul- 
phate, and  a  drop  of  the  blood  expressed  into  the  saline  solution,  and  it  is  noted 
whether  it  sinks  or  floats.  The  operation  is  repeated  with  other  solutions  until 
one  is  found  in  which  the  blood  neither  sinks  nor  floats.  The  sp.  gr.  of  blood 
varies  from  1045-1075,  the  average  sp.  gr.  being  1056-1059. 

(b.)  Haycraft's  Method.— Make  a  mixture  of  toluol  (s.  g.  800)  and  benzyl 
chloride  (s.  g.  iioo)  to  obtain  a  fluid  with  a  s.  g.  of  1070.  Label  this  A. 
Make  another  with  the  s.  g.  1025.     Label  this  B. 

Method. — With  a  pipette  place  a  measured  quantity  of  A  in  a  warm  cylin- 
drical glass.  Add  a  drop  of  the  blood.  It  will  float  ;  now  add  B  until  the 
blood  neither  floats  nor  sinks. 

Suppose  1.5  cc.  of  B  has  been  added  to  i  cc.  of  A,  then 

I     cc.  of  A  (1070)  =1,070 
1,5.  1.5  cc.  of  B  (1025)=  1,537 

2.5  cc  2,607 

Divide  this  by  the  total  volume  2.5  cc.  =  1043,  the  s.  g.  of  the  blood. 

5.  Action  of  a  SaHne  Solution. 

{a.)  To  2  cc.  of  defibrinated  blood  in  a  test-tube  (D)  add  5 
volumes  of  a  10  per  cent,  solution  of  sodium  chloride.  It  changes  to 
a  very  bright,  florid,  brick-red  colour.  Compare  its  colour  with  that 
in  A,  B,  and  C.     It  is  opaque. 

6.  Red  Corpuscles.— Add  to  defibrinated  ox  blood  ^or,  better,  dog's  blood), 
20  volumes  of  a  dilute  solution  of  NaCl  C5-2  per  cent.).  The  red  corpuscles 
subside,  and  the  supernatant  fluid  can  be  poured  off.  Wash  the  corpuscles 
several  times  in  this  way.  They  will  be  required  for  the  preparation  of 
haemoglobin  (p.  65). 

7.  Hgemoglobin  does  not  Dialyse. 

(a.)  Place  a  watery  solution  of  defibrinated  blood  in  a  dialyser 
(a  bulb  form  or  a  parchment  tube),  and  suspend  it  in  a  large 
vessel  of  distilled  water.      Test  the  dialyser  beforehand    to    see 


v.]  THE  BLOOD.  35 

that  there  arc  no  holes  in  it.  If  there  arc  any  fine  pores,  close 
them  with  a  little  white  of  egg,  and  coagulate  it  with  a  hot  iron. 

(b.)  After  several  hours  observe  that  no  hsemoglobin  has 
passed  into  the  water. 

(c.)  Test  the  dilfusate  for  chlorides  (AgN03  +  HNO.). 

8.  Phenomena  of  Coagulation. — Decapitate  a  rat,  and  allow 
the  blood  to  flow  into  a  small  porcelain  capsule.  Within  a  few 
minutes  the  blood  congeals,  and  when  the  vessel  is  tilted  the  blood 
no  longer  moves  as  a  fluid,  but  as  a  solid.  It  tlien  coagulates  com- 
pletely. Allow  it  to  stand,  and  after  an  hour  or  so,  pale-yellow 
coloured  drops  of  fluid— the  serum — are  seen  on  the  surface,  being 
squeezed  out  of  the  red  mass,  the  latter  being  the  clot,  which  con- 
sists of  fibrin  and  the  corpuscles. 

9.  Formation  of  Clot  and  Serum. — Draw  out  a  glass  tube  into  a  fine 
capillary  pipette  at  both  ends,  leaving  a  bulb  in  the  middle,  and  suck  some 
uncoagulated  blood,  either  from  one's  finger,  or  from  the  heart  of  a  frog,  into 
it,  seal  up  the  ends  of  the  tube,  allow  the  blood  to  coagulate,  and  examine 
the  tube  under  a  microscope.  Observe  the  small  red  shrunken  clot,  and  the 
serum  squeezed  out  of  the  latter. 

10.  Frog's  Blood —Coagulation  of  the  Plasma.— Place  5  cc.  of  normal 
saline  (0.75  per  cent,  salt  solution)  in  a  test-tube  surrounded  with  ice. 
Expose  the  heart  of  a  pithed  frog,  and  open  the  ventricle,  allowing  the  blood 
as  it  escapes  to  flow  into  the  normal  saline.  Mix,  and  the  corpuscles  (owing 
to  their  greater  specific  gravity)  after  a  time  subside.  After  they  have 
subsided  remove  the  supernatant  fluid  —  the  plasma  mixed  with  normal 
saline — by  means  of  a  pipette.  Place  it  in  a  watch-glass,  and  observe  that  it 
coagulates. 

11.  Mammalian  Blood. 

(A.)  Study  coagulated  blood  obtained  from  the  slaughter-house. 
Collect  the  blood  of  a  sheep  or  ox  in  a  perfectly  dry  cylindrical 
vessel,  and  allow  it  to  coagulate.  Set  it  aside  for  two  days,  and 
then  observe  the  serum  and  the  clot.  Pour  off  the  pale,  straw- 
coloured  serum,  and  note  the  red  clot,  which  has  the  shape  of  the 
vessel,  although  it  is  smaller  than  the  latter. 

(B.)  If  the  blood  of  a  horse  can  be  obtained,  study  it,  noting  that  tlie  upper 
layer  of  the  clot  is  ])aler  in  colour  ;  this  is  the  bufiFy  coat. 

12.  Circumstances  Influencing  Coagulation. 

Effect  of  Cold. — Place  a  small  ])latinum  capsule — a  brass  or  glass  thimble 
will  do  quite  well— on  a  freezing  mixture  of  ice  and  salt,  decapitate  a  frog  or 
rat,  and  allow  the  blood  to  flow  directly  into  tlie  cooled  vessel.  At  once  it 
becomes  solid  or  congeals,  but  it  is  not  coagulated.  As  soon  as  the  blood 
becomes  solid,  remove  the  tliinible  and  thaw  the  blood  by  placing  it  on  the 
palm  of  the  hand,  wlien  the  blood  becomes  fluid,  so  that  it  can  be  poured  into 
a  watch-glass  ;  if  the  vessel  be  once  more  placed  on  the  freezing  mixture,  tlie 
blood  again  congeals  and  solidifies,  and  on  its  being  removed  becomes  fluid. 
Observe  at  the  same  time  that  the  colour  and  transparency  of  the  blood  are 


36  PRACTICAL   PHYSIOLOGY.  [V. 

altered.  The  blood  becomes  darker  in  colour  and  transparent.  This  is  the 
laky  condition  due  to  the  discharge  of  the  hfcraoglobin  from  the  corpuscles. 
Place  the  vessel  with  the  fluid  blood  on  the  table,  and  it  clots  or  forms  a  firm 
jelly. 

13.  Salted  Plasma— Influence  of  Neutral  Salts  on  Coagu- 
lation.— At  the  slaiigliter-house,  allow  blood  to  run  into  an  equal 
volume  of  saturated  solution  of  sodium  sulphate  (or  one  quarter 
of  its  volume  of  a  saturated  solution  of  magnesium  sulphate) ; 
mix.  Tlie  blood  does  not  clot,  but  remains  fluid.  Place  the 
vessel  aside  on  ice,  and  note  that  the  corpuscles  subside,  leaving 
a  narrow  clear  yellowish  layer  on  the  surface — the  plasma  mixed 
with  the  saline  solution,  and  known  as  salted  plasma.  To  obtain 
sufficient  plasma,  the  blood  must  be  "  centrifugalised "  (page  43), 
to  separate  the  corpuscles  from  the  plasma. 

{a.)  Heat  undiluted  salted  plasma  to  60°  C.  The  fibiinogen  is 
precipitated  at  56°  C.  Filter.  The  filtrate  will  not  coagulate, 
even  after  the  addition  of  fibrin-ferment  and  CaCl2,  as  there  is  no 
fibrinogen  present. 

(A.)  Place  1 5  cc.  of  the  salted  plasma  in  a  tall,  narrow,  cylindrical, 
stoppered  glass  tube.  Add  crystals  of  sodium  chloride,  and  shake 
the  whole  vigorously,  when  a  white  flocculent  precipitate  is  thrown 
down.  Allow  the  precipitate  to  subside.  Decant  tlie  supernatant 
fluid.  Filter  through  a  filter  moistened  with  a  saturated  solution 
of  sodic  chloride,  and  wash  the  precipitate  on  the  filter  with  a 
saturated  solution  of  sodic  chloride.  This  is  the  plasmine  of  Denis. 
With  a  spatula,  scrape  the  washed  precipitate  ofl'  the  filter. 

Dissolve  the  plasmine  in  a  small  quantity  of  distilled  water, 
and  filter  quickly.  The  filtrate,  if  set  aside,  will  clot  after  a 
time.  It  is  better  to  do  the  several  operations  rapidly  to  ensure 
success,  but  I  have  frequently  found  coagulation  occur  when  the 
plasmine  was  not  dissolved  in  water  until  many  hours  after  it  was 
deposited. 

14.  Oxalate  Plasma. — Oxalate  of  potassium  prevents  blood  from 
coagulating  wlien  present  to  the  extent  of  0.2  per  cent.  Dissolve 
I  gram  of  potassium  oxalate  in  10-20  cc.  of  normal  saline,  place 
it  in  a  vessel  capable  of  holding  500  cc,  and  allow  blood  to  run 
in  to  fill  the  vessel.  Mix  the  two  fluids.  The  blood  does  not 
coagulate,  but  remains  fluid.  Centrifugalise  it  to  obtain  •  the 
oxalate  plasma,  which  may  be  siphoned  off.  The  oxalate  pre- 
cipitates— as  oxalate  of  lime — the  calcium  which  is  necessary  for 
coagulation. 

{a.)  To  oxalate  plasma,  add  a  few  drops  of  a  2  per  cent, 
calcium    chloride    solution  =  coagulation,    and    more    quickly   at 

40°  c. 


v.]  THE  BLOOD.  37 

15.  Defibriiiated  Blood. — In  a  slaughter-house  allow  the  blood 
from  an  animal  to  run  into  a  vessel,  and  with  a  bundle  of  twigs 
beat  or  whip  the  blood  steadily  for  some  time.  Fine  white  fibres 
of  fibrin  collect  on  the  twigs,  while  the  blood  remains  fluid.  This 
is  defibrinated  blood,  which  does  not  coagulate  spontaneously. 

16.  Fibrin.  — Wash  away  the  colouring-matter  with  a  stream  of 
water  from  the  twigs  until  the  fibrin  becomes  quite  white. 

(a.)  Physical  properties  :  it  is  a  white,  fibrous,  elastic  substance. 
Stretch  some  fibres  to  observe  their  extensibihty ;  on  freeing  them, 
they  regain  their  shape,  showing  their  elasticity. 

{b.)  Place  a  few  fibres  in  absolute  alcohol  to  rob  them  of  water.  They 
become  brittle  and  lose  their  elasticity. 

(c.)  Place  a  small  quantity  of  fibrin  in  a  test-tube  with  some 
0.2  per  cent,  hydrochloric  acid  in  the  cold.  It  swells  up  and 
becomes  clear  and  transparent,  but  does  not  dissolve. 

{d. )  Repeat  (r. ),  but  place  the  test-tube  in  a  water-bath  at  60**  C.  ;  part  of 
the  fibrin  is  dissolved,  forming  acid-albumin.     Test  for  the  latter  (Lesson  I.  7). 

(e.)  Place  some  hydric  peroxide  over  fibrin  in  a  watch-glass ; 
bubbles  of  oxygen  are  given  ofi".  Immerse  a  flake  in  freshly- 
prepared  tincture  of  guaiacum  (5  per  cent,  solution  of  the  pure  resin 
in  alcohol),  and  then  in  hydric  peroxide,  when  a  blue  colour  is 
developed,  due  to  the  ozone  Hberated  by  the  fibrin  striking  a  blue 
with  the  resin.  If  the  fibrin  contains  much  water,  it  is  preferable 
to  place  it  first  of  all  for  a  short  time  in  rectified  spirit  to  remove 
the  water.  [Other  substances  give  a  blue  colour  under  similar 
conditions.] 

(/.)  Place  some  fibrin  in  water  in  a  test-tube.  Note  that  it  gives  the 
xanthoproteic  reaction  and  Millon's  test  (Lesson  I.  1). 

((/.)  Prick  a  finger  with  a  needle,  collect  a  drop  of  blood  on  a  microscopic 
slide,  cover,  and  examine  under  a  microscope  (  x  350).  After  a  time,  observe 
the  formation  of  threads  of  fibrin  between  the  rouleaux  of  coloured  blood - 
corpuscles. 

17.  II.  Blood-Serum. — By  means  of  a  pipette  remove  the  serum 
from  the  coagulated  blood  or  siphon  it  off  (Lesson  V.  8).  If  a 
centrifugal  apparatus  is  available,  any  suspended  blood-corpuscles 
can  easily  be  separated  by  it.  Note  its  straw-yellow  colour  and 
musky  odour.     Its  reaction  alkaline.     Its  sp.  gr.  =  1034. 

General  Proteid  Reactions. 

(a.)  Dilute  i  volume  of  serum  with  10  volumes  of  normal  saline 
or  salt  solution. 

(6.)  Test  separate  portions  by  neutralisation  and  heat  =  coagu- 
lation ;  nitric  acid  and  the  subsequent  addition  of  ammonia;  acetic 


38  PRACTICAL  PHYSIOLOGY.  [V. 

acid  and  ferrocyanide  of  potassium;  Millon's  reagent;  and  the 
NaHO  and  CuSO^  reaction  (Lesson  I.  1).  Alcohol  causes  coagu- 
lation. 

{(•.)  Saturate  it  with  ammonium  sulphate.  ThLs  precipitates  all 
the  proteids,  globulin  and  albumin.  Filter ,  the  filtrate  is  proteid- 
free. 

Study  its  individual  proteids. 

(A.)  Preparation  of  Serum-Globulin  (Paraglobulin). 

(a.)  A,  Schmidt's  Method.— To  lo  cc.  of  serum  add  200  cc.  of  ice-cold 
water,  and  pass  a  stream  of  carbon  dioxide  through  it  for  some  time  =  a  white 
precipitate  of  serum-globulin.  This  method  does  not  precipitate  it  entirely. 
No  precipitate  is  obtained  unless  the  serum  be  diluted. 

(h.)  Panum's  Method. — Dilute  i  cc.  of  serum  with  15  cc.  of  water;  add  5 
drops  of  a  2  per  cent,  solution  of  acetic  acid  =  a  white  precipitate  of  serum- 
globulin,  or,  as  it  was  called,  "  serum-casein."  AU  the  serum-globulin  is  not 
precipitated. 

(c.)  Hammarsten's  Method. — Saturate  serum  with  magnesium 
sulphate,  and  shake  briskly  for  some  time.  An  abundant  precipi- 
tate of  serum-globulin  is  obtained.  Allow  the  excess  of  the  salt 
and  the  precipitate  to  settle.  The  undissolved  crystals  fall  to  the 
bottom,  and  on  their  surface  is  precipitated  a  dense  white  fiocculent 
mass  of  serum-globuUn.  Filter.  "Wash  the  precipitate  on  the 
filter  with  a  saturated  solution  of  magnesium  sulphate ,  add  a  httle 
distilled  water  to  the  precipitate.  It  is  dissolved,  i.e.j  it  is  a  globulin, 
and  is  insoluble  in  excess  of  a  neutral  salt,  but  is  dissolved  by  a 
weak  solution  of  the  same.  The  solution  does  not  coagulate  spon- 
taneously. It  gives  all  the  reactions  for  proteids  with  the  special 
reactions  of  a  globulin. 

(d.)  Kauders  Method. — Add  to  serum  half  its  volume  of  a 
saturated  solution  of  ammonium  sulphate  (i.e.,  half  saturate  it)  = 
precipitate  of  the  globulin.  Complete  saturation  precipitates  the 
albumin  as  well 

Only  methods  (c)  and  (d)  are  now  used.  Kauder's  method  enables 
one  rapidly  to  separate  the  globulin  and  then  the  albumin  by  the 
use  of  one  salt. 

(^.)  Allow  a  few  drops  of  serum  to  fall  into  a  large  quantity  of 
water,  and  observe  the  milky  precipitate  due  to  the  presence  of  a 
globulin  =  serum-gloiHilin.  This  is  best  observed  by  placing  a  dead 
black  surface  behind  the  vessel  of  water.  "We  can  then  trace  the 
*'  milky  way  "  of  the  falling  drops  of  serum  as  they  traverse  the 
water. 

(B.)  Serum-Albumin. — From  (A.),  (c),  filter  ofl'  the  precipitate, 
and  test  the  filtrate  for  the  usual  proteid  reactions.  It  is  evident 
that  the  filtrate  still  contains  a  proteid,  which  is  serum-albumin 
(Lesson  1.  5,  2).     To  the  filtrate  add  sodic  sulphate,  when  serum- 


v.]  THE  BLOOD.  39 

albumin  is  precipitated.     Sodic  sulphate  alone,  however,  gives  no 
precipitate  with  pure  serum. 

18.  Precipitation  of  Senim  Proteids  by  Other  Salts. 

(a.)  Precipitate  blood -serum  with  potassic  phosi)hate.  All  the  proteids  are 
thrown  down  after  prolonged  shaking. 

{b.)  Precipitate  blood-serum  with  magnesie  sulphate  and  sodic  sulphate,  or 
the  double  salt  sodio-magnesic  sulphate.     All  the  proteids  are  thrown  down. 

19.  Coagulation  Temperature  of  Serum-Proteids. — Saturate 
serum  witli  MgSO^.  Filter,  keep  the  filtrate,  label  it  B.  Wash 
the  precipitate,  i.e.,  the  serum-globulin  with  saturated  solution  of 
magneshim  sulphate  until  the  washings  give  no  reaction  for  albu- 
min. This  takes  a  long  time,  and  had  better  be  done  previously 
by  the  demonstrator.  Dissolve  the  precipitate  in  distilled  water, 
which  gives  an  opalescent  solution.  Label  it  A.  Acidify  it 
slightly  with  a  drop  of  2  per  cent,  acetic  acid,  and  determine  the  tem- 
perature at  which  it  coagulates  by  the  method  stated  on  p.  11. 
The  liquid  in  the  test-tube  should  just  cover  the  bulb  of  the 
thermometer.     Coagulation  takes  place  about  75°  C. 

The  filtrate  B  contains  the  serum-albumin.  Dilute  it  with  an 
equal  volume  of  water,  faintly  acidify  and  heat,  as  above.  A  pre- 
cipitate falls  about  77-79°  C.  (B),  and  on  filtering  this  off,  and 
again  acidifying,  another  precipitate  is  obtained  on  heating  to 
84-86°  C. 

20.  Preparation  of  Fibrinogen  from  Hydi'ocele  Fluid,  which 

does  not  coagulate  spontaneously. 

{a.)  Dilute  10  cc.  of  hydrocele  fluid  with  150  to  200  cc.  of  water,  and  pass 
through  it  for  a  considerable  time  a  stream  of  carbon  dioxide,  when  there  is 
precipitated  a  small  quantity  of  a  somewhat  slimy  white  body,  fibrinogen. 
(Schmidt's  method. ) 

(b.)  Half  saturate  hydrocele  fluid  with  sodium  chloride  solution 
by  adding  to  it  an  equal  vohime  of  saturated  solution  of  sodium 
chloride.  Fibrinogen  is  precipitated  in  small  amount.  Filter,  and 
on  adding  MgSO^,  serum-globulin  is  precipitated,  so  that  hydrocele 
fluid  contains  both  fibrinogen  and  serum-globulin. 

21.  Coagulation  Experiments. 

(a.)  Andrew  Buchanan's  Experiment. — Mix  5  cc.  fresh  serum 
(preferably  from  horse's  blood)  with  5  cc.  hydrocele  fluid  and 
keep  the  mixture  at  35°  C.  for  some  hours,  when  coagulation  occurs, 
a  clear  pellucid  clot  of  fibrin  being  obtained.  Coagulation  takes 
place,  and  is  due  to  the  action  of  fibrin-ferment  on  fibrinogen  and 
not  to  the  presence  of  serum-globulin,  as  hydrocele  fluid  in  addition 
to  fibrinogen  contains  this  body. 


40 


PRACTICAL  PHYSIOLOGY. 


[V. 


(b.)  To  5  cc.  of  hydrocele  fluid  add  some  solution  of  fibrin- 
ferment,  and  keep  in  a  water-bath  at  40°  C.  coagulation  takes 
place. 

(r.)  To  2  CO.  of  salted  plasma,  prepared  as  in  Lesson  V.  13 
(which  is  known  to  clot  slowly  on  the  addition  of  water),  add  lo 
volumes,  i.e.,  20  cc.  of  a  watery  solution  of  fibrin-fennent,  pre- 
pared by  the  demonstrator  =  coagulation. 

(d.)  Add  to  oxalate-pksma  (Lesson  Y.  14)  a  few  drops  of  a  2 
per  cent,  calcium  chloride  solution.  It  coagulates,  and  more  quickly 
at  40°  C.  The  CaCl2  supplies  the  calcium  necessary  for  the  forma- 
tion of  fibrin. 

(e.)  Effect   of  Temperature   on   Coagulation. — Dilute  sodium 
sulphate  plasma  with  10  volumes  of  water,  and  place  some  in  test- 
tubes  A,  B,  C,  D. 

A  clots  slowly  or  not  at  aU. 
Place  B  in.  water-bath  at  40° 
C.     It  clots  more  quickly. 

To  C  add  a  small  quantity 
of  fibrin-ferment  (p.  40),  dis- 
solved in  a  little  calcium 
chloride. 

To  D  add  serum.  Keep  C 
and  D  at  40°  C.  They  coagu- 
lated rapidly,  because  of  the 
abimdance  of  fibrin-ferment. 

22.  Preparation  of  Fibrin-Fer- 
ment.— It  must  be  kept  in  stock. 
FIG.  i6.--Exsiccator  for  Drying  a  Precipitate  Precipitate  blood-serum  with  a  large 
over  Sulphunc  Acid.    b.  Glass  bell-jar,  cover-  „  „„„f,     f  „i„^v„i    „^n„  ,4.  4.v„  „^^;^„o 
ing  vessel  with  sulphuric  acid  (c),  and  support  excess  of  alcohol,  collect  the  copious 
(d)  for  the  deposit  or  precipitate.  precipitate,   consisting  of  the   pro- 

teids  and  fibrin-ferment.  Cover  it 
with  absolute  alcohol,  and  allow  it  to  stand  at  least  a  month,  when  the  pro- 
teid.s  are  rendered  insoluble.  Dry  the  precipitate  at  35°  C,  and  afterwards 
over  suli>huric  acid  (fig.  16).  Keep  it  as  a  dry  powder  in  a  well -stoppered 
bottle.  When  a  solution  is  required,  extract  some  of  the  dry  powder  with  100 
volumes  of  water  ;  filter.     The  filtrate  contains  the  ferment. 

23.  Salts  and  Sugar  of  Serum. — The  usual  salts  may  be  tested 
for  directly  with  serum  diluted  with  water,  or  the  following  method 
may  be  adopted  : — 

Dilute  blood  and  boil  it ;  filter. 


Colourless  filtrate,  which  can  be  tested 
for  salts  and  sugar. 


Coagulum  coloured   brown  by  ha 
matin. 


v.]  THE   BLOOD.  4 1 

The  blood  is  licated  with  6  to  8  times  its  volume  of  water,  and  slightly 
acidulated.  The  filtrate  is  evaporated  to  a  small  bulk.  When  a  drop  of  the 
concentrated  filtrate  is  placed  on  a  slide,  cubes  of  common  salt  separate  out. 

To  the  colourless  filtrate  of  23 

(a.)  Add  silver  nitrate  =  white  curdy  precipitate  soluble  in 
ammonia,  but  insoluble  in  nitric  acid  =  cJiloride-^. 

{!).)  Add  barium  chloride  =  white,  heavy  precipitate  insoluble  in 
nitric  acid  =  sulphates. 

(c.)  Add  nitric  acid  and  molybdate  of  ammonium  and  heat  = 
yellow  ^iQoi'^ii^iQ  ^  phosphates. 

(rZ.)  Test  with  Fehling's  solution  or  CuSO^  and  NaHO  and  boil 
=  red  cuprous  oxide  =  reducing  sugai\  which  is  glucose. 


ADDITIONAL  EXEKCTSES. 

24.  To  Obtain  Clear  Sernm.  —The  best  way  to  obtain  this  is  by  means  of  a 
centrifugal  apparatus  ;  but  il  the  serum  contain  blood-corpuscles,  a  fairly 
clear  fluid  may  be  obtained  by  placing  it  in  a  vessel  like 
(fig.  17).  It  consists  of  the  separated  top  ot  a  wide  flask 
provided  with  a  cork  in  the  neck,  and  in  the  cork  is  an 
adjustable  tube  provided  with  a  clip.  When  the  serum 
is  placed  in  the  apparatus,  it  must  be  aViove  the  level 
of  the  tube.  On  opening  the  clip,  the  clear  serum  can  be 
drawn  oil  without  di.sturbing  the  deposit. 

25.  Preparation     of    Serum  -  Albumin   and   Serum- 
Globnlin.- Dilute  clear  serum  with  three  volumes  of  a  ^'JJ,^  obt^i,iing*cnea? 
saturated  solution  of  neutral  ammonium  sulphate,  and     Seruni. 

add  crystals  of  the  same  salt  to  complete  saturation. 
Filter.  The  deposit  contains  the  two  above-mentioned  substances,  and  is 
washed  with  a  saturated  solution  of  (NHj^^SO^.  The  deposit  is  then  dis- 
solved in  the  smallest  possible  amount  of  water  and  dialysed  in  a  ])archment 
tube.  In  j)roportion  as  the  salt  dialyses,  the  serum-globulin  is  deposited  as  a 
white  powder  in  the  dialysirig  tube,  whilst  the  seruni -albumin  remains  in 
solution.  It  is  not  difiicult  to  devise  an  a])})aratus  whereby  the  water  is 
kept  flowing,  and  even  the  dialysis  tui)e  kept  in  motion  in  the  running  water, 
provided  one  has  some  motor  power  at  hand.  (S.  Lea,  Journal  of  Fhysiology , 
xi.  p.  226). 

After  complete  dialysis  the  fluid  is  filtered,  the  deposited  serum -globulin  is 
collected  and  washed.  The  filtrate— which  contains  the  serum-albumin — is 
carefully  neutralised  with  ammonia,  again  dialysed,  filtered  and  concentrated 
at  40"  C.  After  it  is  cold,  the  serum-albumin  is  ])recipitated  at  once  by  strong 
alcohol,  expressed,  washed  with  ether  and  alcohol,  and  dried. 


42 


PRACTICAL   PHrSIOLOGY. 


[V. 


Serum-albumin  is  completely  precipitated  from  its  solution  by  ammonium 
sulphate,  but  not  at  all  by  magnesic  sulphate.  A  solution,  free  from  serum- 
globulin,  containing  1-1.5  percent,  of  salts,  coagulates  at  about  50"^,  >vith  5 
per  cent,  of  NaCl  at  75°-8o^  C. 

26.  Estimation  of  Grape-Sugar  in  Blood. — (a.)  Place  20  grams  of  crystal- 
lised sodic  sulphate  in  each  of  three  porcelain  capsules,  and  to  each  add  exactly 
20  grams  of  the  blood  to  be  investigated.  Mix  the  blood  and  salt  together. 
Boil  them  until  the  froth  above  the  clot  becomes  white,  and  the  clot  itself 
does  not  present  any  red  specks.  Weigh  again,  and  make  up  the  loss  by 
evaporation  by  the  addition  of  water.  The  whole  is 
~  then  placed  in  a  small  press,  and  the  fluid  part   ex- 

pressed, collected  in  a  capsule,  and  afterwards  filtered. 
The  filtrate  is  placed  in  a  burette. 

In  a  flask  place  i  cc.  of  Fehling's  solution,  and  to  it 
add  a  few  .-mall  pieces  of  caustic  potash  and  20  cc.  of 
distilled  water.  Boil  this  fluid,  and  from  the  burette 
allow  the  clear  filtrate  of  the  blood  to  drop  into  the 
boiling  dilute  Fehling's  solution  until  the  latter  loses 
every  trace  of  its  blue  colour  (fig.  18).  As  in  all  sugar 
estimations,  the  process  must  be  repeated  several  times 
to  get  accurate  results.  Hence  the  reason  why  several 
capsules  are  prepared. 

Read  off,  on  the  burette,  the  number  of  cc  of  the 
filtrate  used,  g.gr.  =71  cc     The  formula 


S^ 


8 


in  grams  the  weight  of  sugar  per  kilogram  of  blood. 
{Bernard.) 

(b.)  In  Seegen's  Method,  which  may  be  taken  as 
the  type  of  the  newer  methods,  the  proteids  are  pre- 
cipitated by  ferric  acetate.  The  blood  is  diluted  with 
8-10  times  its  volume  of  water,  acidulated  with  acetic 
acid,  and  heated.  When  the  precipitation  of  proteids 
commences,  render  the  mixture  strongly  acid  by  the 
addition  of  acetate  of  soda  and  perchloride  of  iron  ; 

then  add  suflBcient  sodic  carbonate  until  the  mixture 

vt      r  _-r         V-  A         ^^  faintly  acid,  and  boil.     Allow  it  to  cool,  and  filter 

StisforESfmatinjftlfe  ^^  through  a  fine  cloth  filter,  free  from  starch.     The 

Sugar  in  Blood.  filtrate   ought    to    be    clear.      The    residue    on    the 

filter  is  washed  several   times  with  water,   and  the 

remaining  fluid  in  it  expressed  by  means  of  a  small  hand-press.   The  expressed 

fluid  is  then  mixed  with  the  clear  filtrate.    If  the  mixture  has  a  slight  reddish 

tint  from  the  admixture  of  a  small  quantity  of  blood-pigment     Add  a  drop 

or  two  of  perchloride  of  iron  to  precipitate  the  last  traces  of  the  proteids. 

Filter  again.     The  sugar  in  the  filtrate  is  estimated  in  the  usual  way  by 

means  of  Fehling's  solution. 

27.  Ash  of  Hsemoglobln. — Incinerate  a  small  quantity  of  oxy-hsemoglobin 
in  a  platinum  capsule.  This  is  done  in  the  manner  shown  in  fig.  19,  where 
the  capsule  is  placed  obliquely,  and  its  contents  heated  in  a  Bunsen-flame 
until  only  the  ash  remains.     The  ash  is  red,  and  consists  of  oxide  of  iron. 

(a.)  Dissolve  a  little  in  hydrochloric  acid  ;  add  })otassic  sulphocyanide  =  a 
^ed  precipitate,  -I-  ferrocyanide  of  potassium  =  a  blue  precipitate. 


VI.] 


THl:  COLOURED  BLOOD  CORPUSCLES. 


43 


28.  The    Centrifugal    Machine. — Precipitates    or    very   minute    particles 
suspended    in    a   fluid,    e.ri.,    blood- 
corpuscles  in  serum  may   be   readily 
separated  by  this  apparatus. 

The  liquid  is  placed  in  strong  glass 
tubes,  and  these  are  in  turn  placed 
in  metallic  cases,  which  can  move  on 
a  horizontal  axis,  the  cases  themselves 
being  placed  in  a  horizontal  disc 
which  is  driven  at  the  rate  of  looo 
revolutions  per  minute ;  this  causes 
the  tubes  to  take  a  horizontal  posi- 
tion, and  after  30-40-60  minutes 
rotation  the  precipitate  or  other  sus- 
pended particles  are  found  at  the 
outer  end  of  the  tube.  The  serum 
can  thus  be  obtained  perfectly 
zorpuscleless. 

There  are  various  forms  of  this 
apparatus.  Some  can  be  driven  by 
the  hand  and  yield  small  quantities 
of  fluid,  such  as  those  sold  by 
Muencke  of  Berlin  (see  Stirling's 
Outlines  of  Practical  Histulogy,  p.  94, 
2  Ed.  1893)  or  that  made  by  Watson  ^iq  i 
&  Laidlaw  of  Glasgow.  When  large 
quantities  of  fluid  are  required,  that 

made  by  Fr.  Runne  of  Basel  is  one  of  the  best.  It  requires  a  water  01 
gas-motor  to  drive  it.  At  the  present  time  Runue's  "Werkstatte  f.  prac. 
Mechanik  "  are  situated  in  Heidelberg. 


Method  of  Incinerating  a  Deposit  to 
Obtain  the  Ash. 


LESSON  VI. 

THE  COLOURED  BLOOD  CORPUSCLES. 

SPECTRA  OF  HAEMOGLOBIN  AND  ITS  COMPOUNDS. 


Enumeration  of  the  Corpuscles.— Several  forms  of  instruments 
are  in  use,  e.//.,  those  of  Malassez,  Zeiss,  Bizzozero,  and  Gowers. 

1.  The  Hsemocytometer  of  Gowers  (fig.  20)  can  be  used  with 
any  microscope,  and  consists  of — 

(a.)  A  small  pipette,  which,  when  filled  to  the  mark  on  its  stem, 
holds  995  c.mra.  (fig.  20,  A). 

{b.)  A  capillary  tube  to  hold  5  c.mm.  (B). 

(c.)  A  small  glass  jar  in  which  the  blood  is  diluted  (D). 

{(1.)  A  glass  stirring  rod  (E). 

(e.)  Fixed  to  a  brass  plate  a  cell  }  of  a  miUimetre  deep,  and  with 


44 


PRACTICAL  PHYSIOLOGY. 


[VI. 


its  floor  divided  into  squares  ^o  nim.,  in  which  the  blood-corpuscles 
are  counted. 

(/".)  The  diluting  solution  consists  of  a  solution  of  sodic  sulphate 
in  distilled  water — sp.  gr.  1025. 

2.  Mode  of  Using  the  Instrument. 

(a.)  By  means  of  the  pipette  (A)  place  995  c.mm.  of  the  dilut- 
ing solution  in  the  mixing  jar  (D). 

(h.)  Puncture  a  finger  near  the  root  of  the  nail  with  the  lancet 
projecting  from  (F),  and  with  the  pipette  (B)  suck  up  5  c.mm.  of 


Fig.  20.— Gowers'  Haemocj^meter.  A.  Pipette  for  measuring  the  diluting  solution  ;  B. 
Fur  measuring  the  blofxl  ;  C.  Cell  with  divisions  on  the  floor,  mounted  on  a  slide,  to 
which  sjirings  are  fixed  to  secure  the  cover-glass ;  D.  Vessel  in  which  the  solution  is 
made  ;  E.  Spud  for  mixing  the  blood  aud  solution  ;  F.  Guarded  spear-pointed  needle. 

the  blood,  and  blow  it  into  the  diluting  solution,  and  mix  the  two 
with  the  stirrer  (E). 

(c.)  Place  a  drop  of  the  mixture  on  the  centre  of  the  glass  cell 
(C),  see  that  it  exactly  fills  the  cell,  and  cover  it  gently  with  the 
cover-glass,  securing  the  latter  with  the  two  springs.  Place  the 
cell  with  its  plate  on  the  stage  of  a  microscope,  and  focus  for  the 
squares  ruled  on  its  base. 

(d.)  When  the  corpuscles  have  subsided,  count  the  number  in 
ten  squares,  and  this,  when  multipUed  by  10,000,  gives  the  number 
in  a  cubic  millimetre  of  blood. 


VI.] 


THE  COLOURED  BLOOD  CORPUSCLES. 


45 


(e.)  "Wash  the  instrument,  and  in  cleaning  the  cell  do  this  witli 
a  stream  of  distilled  water  from  a  wash-bottle.  Take  care  not  to 
brush  the  cell  with  anything  rougher  than  a  camel's-hair  pencil,  to 
avoid  injuring  the  lines. 

Each  square  has  an  area  of  y^  of  a  square  mm.,  so  that  lo 
squares  have  an  area  of  y^^  of  a  square  mm.  As  the  cell  is  ^  mm. 
deep,  the  volume  of  blood  in  lo  squares  is  yg-  x^  =  -^^  c.mm.  On 
counting  the  number  of  corpuscles  in  lo  squares,  and  multiplying 
by  50,  this  will  give  the  number  in  i  c.mm,  of  the  diluted  blood. 
On  multiplying  this  by  ^~j  w'e  get  the  number  in  i  c.mm.  before 
dilution.  Thus  we  arrive  at  the  reason  why  we  multiply  the 
number  in  10  squares  by  10,000  to  get  the  number  of  corpuscles  in 
I  c.mm.  of  blood. 


HAEMOGLOBIN  AND  ITS  DERIVATIVES. 


^y 


c 


? 


3.  Preparation  of  Haemoglobin  Crystals,  (C,,oo^^9GoNi54C>i79SFe) 
(a.)  Rat's  Blood.— Place  a  drop  of  detibrinated  rat's  blood  on  a 

slide,  add  three  or  four  drops  of  water, 

mix,  and  cover  with  a  cover-glass.    Ex- 
amine with  a  microscope ;  after  a  few 

minutes   small    crystals   of    oxy-hiemo- 

globin   will  begin   to   form,    especially 

at  the  edges  of   the   preparation,    and 

gradually   grow  larger   in  the  form  of 

thin  rhombic  plates  arranged  singly  or 

in  groups  (fig.  21). 

{h.)  Guinea-Pig's  Blood.— Treat  the 

blood  of  a  guinea-pig  as  directed   for 

the  blood  of  a  rat.    Tetrahedral  crystals 

are  obtained.     Mount  some  defibrinated 

blood    in    Canada    balsam.       Crystals 

form. 

/    \  T\     1    -ni     J       _,  r  1   n-,    •      .    1       FiQ-  21.— 5-8emoglobiii  Crystals 

(c.)  Dog's  Blood.— To  15  cc.  of  defibrinated  from  Rat's  Blood, 

dog's    blood   add,    drop    by   drop,    i    oc.    or 

so  of  ether,  shaking  the  tube  after  each  addition  of  ether.  By  this  means 
tlie  blood  is  rendered  lakj/,  a  condition  which  is  recognised  by  incHning 
the  tube,  and  observing  that  the  film  of  blood  left  on  it,  on  bringing  the 
tube  to  the  vertical  again,  is  transparent.  Add  no  more  ether,  but  })lace  the 
tube  in  a  freezing  mixture  of  ice  and  salt  ;  as  the  temperature  falls,  crystals 
of  h.nemoglobin  separate.  If  the  crystals  do  not  separate  at  once,  keep  the 
tube  in  the  freezing  mixture  for  one  or  two  days.  Examine  the  crystals 
microscopically.  Arthus  finds  that  dog's  blood,  containing  i  per  cent,  of 
sodic  fluoride,  after  standing  for  several  days,  according  to  the  surrounding 
temperature,  deposits  crystals  of  Hb. 


46 


PRACTICAL   PHYSIOLOGY. 


[VI. 


4.  Ozone  Test  for  Haemoglobin. — Mix  some  freshly-prepared 
alcoholic  soUition  of  guaiacum  with  ozonic  ether;  the  mixture 
becomes  turbid,  and  on  adding  even  a  dilute  solution  of  haemo- 
globin, a  blue  colour  results,  due  to  oxidation  of  the  resin  by  the 
ozone  liberated  from  the  ozonic  ether  by  the  haemoglobin. 

5.  Spectroscopic  Examination  of  Blood. — Use  a  small  Brown- 
ing's straight- \dsion  spectroscope  (fig.  22). 


Fig.  22.— Browning's  Strsught- Vision  Spectroscopa 


Preliminary. — Observe  the  solar  spectrum  by  placing  the 
spectroscope  before  the  eye,  and  directing  it  to  bright  daylight. 
Note  the  spectrum  from  the  red  to  the  violet  end,  with  the  inter- 
mediate colours,  and  focus  particularly  the  dark  Fraunhofer's  lines, 

known  as  D  in  the  yellow,  E  in 
the  green,  h,  and  F,  their  position 
and  relation  to  the  colours.  ^lake 
a  diagram  of  the  colours,  and  the 
dark  lines,  indicating  the  latter  by 
their  appropriate  letters. 

('7.)  Fix  the  spectroscope  in  a 
suitable  holder,  and  direct  it  to  a 
gas-flame,  the  edge  of  the  flame 
being  towards  the  sht  in  the  spec- 
troscope, noting  that  the  spectrum 
shows  no  dark  Fraunhofer  Hnes. 

(6.)  Fuse  a  piece  of  platinum 
wire  in  a  glass  tube,  and  make  a 
loop  at  the  free  end  of  the  wire 
(fig.  23).  Dip  the  platinum  wire 
in  water  and  then  in  common 
salt,  and  burn  the  salt  in  the  gas- 
flame,  having  previously  directed  the  spectroscope  towards  the  gas- 
flame,  and  so  arranged  the  latter  that  it  is  seen  edge-on.  Note  the 
position  of  the  bright  yellow  sodium  line  in  the  position  of  the 
line  D, 


FlO.  23. — Stand  for  Platinam  Wire  for 
Sodium  Flame. 


VI.] 


THE   COLOURED    BLOOD   CORPUSCLES. 


47 


6.  I.  Spectrum  of  Oxy-hsemoglobin. 

(a.)  Begin  with  a  strong  solution  and  gradually  dilute  it.  Place 
some  defibrinated  blood  in  a  test-tube,  and  observe  its  opacity  and 
bright  scarlet  colour, 

(fj.)  Adjust  the  spectroscope  as  follows  : — Light  a  fan-tailed  gas 
burner,  fix  the  spectroscope  in  a  suitable  holder,  and  between  the 
light  and  the  slit  of  the  spectroscope  place  a  test-tube  containing 
the  blood  or  its  solution.  Focus  the  lo?ic/  image  of  the  gas-flame  on 
tlie  slit  of  the  spectroscope.  The  focal  point  can  be  readily  ascer- 
tained by  holding  a  sheet  of  white  paper  behind  the  test-tube. 


Red.     Orange.         Yellow. 


Green. 


Blue. 


A    a 

1 

B 

...I.M.I 

60 

Mnlnnl.n 

D                     E  b                F 

30          70         80          00         100         iro 

1 

■p 

M^^^^^^^^H 

2 

!■ 

1 

L 



in 

4 

1 

m 

I 

Fio.  24. — Spectra  of  Haemoglobin,  and  its  Compounds.  1.  Oxy-hgemoglobin,  0.8  per  cent,; 
2.  Oxy-haemoglobin,  a  18  per  cent.;  3.  Carbonic  oxide  haemoglobin;  4,  Reduced  haemo- 
globin, 

(c.)  Add  10  to  15  volumes  of  water,  and  note  that  only  the  red 
part  of  the  spectrum  is  visible.  INIake  a  sketch  of  what  you  see, 
noting  the  dilution. 

(d.)  Add  more  water  until  the  green  appears,  and  observe  that 
a  single  dark  absorption-band  appears  between  the  red  and  green 
(fig.  24,  i).  Continue  to  dilute  until  this  single  broad  band  is 
resolved  into  two  by  the  transmission  of  yellow-green  light.  Burn 
a  bead  of  sodic  chloride  in  the  gas-flame,  to  note  distinctly  the 
position  of  the  D  Hne,  and  observe  that  of  the  two  absorption 
bands  the  one  nearest  D,  conveniently  designated  by  the  letter  a, 
is   more   sharply   defined   and   narrower;    while   the   otlier,   cou- 


48 


PRACTICAL  PHYSIOLOGY. 


[VI. 


veniently  designated  by  the  letter  ^,  nearer  the  violet  end,  is 
broader  and  fainter.  At  the  violet  end  the  spectrum  is  shortened 
by  absorption  (tig.  24,  2). 

{e.)  Continue  to  dilute  the  solution,  and  note  that  the  band  near 
the  violet  end  is  the  first  to  disappear. 

Usijig  coloured  cJuiUcs  or  pencils,  sketch  the  appearances  seen  with 
each  dilution,  and  indicate  opposite  each  the  derjree  of  the  latter. 

(/■.)  A  very  instructive  method  is  to  make  a  pretty  strong  solu- 
tion of  blood,  showing  only  one  undivided  band.  Place  a  little 
of  this  in  a  test-tube,  and  pour  in  water,  so  that  the  water  mixes 
but  shghtly  with  the  upper  strata  of  the  blood.  Examine  the 
solution  spectroscopically,  moving  the  tube  so  as  to  examine  first 


Fl(J.  25.— Graphic  ij^epresentation  of  the 
Absorption  of  Light  in  a  Spectrum 
by  Sohitions  of  Reduced  Hb,  of  dif- 
ferent strengths.  The  shading  indi- 
cates the  amount  of  absorption  of  the 
spectrum,  and  the  numbers  at  the 
side  the  strength  of  the  solution. 


FlO.  26.— Graphic  Representation  of  the 
Absorption  of  Lisiht  in  a  Spectrum  by 
Solutions  of  O-xy-hfemoglobin,  of  differ- 
ent strengths.  Tthe  shading  indicates 
the  amount  of  absorption  of  the  spec- 
trum, and  the  numbers  at  the  side  the 
strength  of  the  solution. 


the  deeper  strata  of  fluid  until  the  surface  is  reached.  At  first 
a  single  band  is  seen ;  but  as  the  solution  is  more  dihite  above, 
the  two  bands  begin  to  appear,  and  as  the  solution  gets  weaker  above, 
the  /?-band  disappears,  until,  finally,  with  a  very  weak  solution, 
such  as  is  obtamed  in  the  upper  strata  only,  the  a-band  alone  is 
visil:)le. 

Fig  26  shows  the  amount  of  light  absorbed  by  solutions  of  oxy- 
haemoglobin  (i  cm.  in  thickness)  and  of  various  strengths. 

7.  II.  Hgemoglobin. 

(a.)  To  a  solution  of  oxy-hrpmoglobin  showing  two  well-defined 
absorption-bands,  add  a  few  drops  of  ammonium  sulphide,  and 
warm  (jentlij,  when  the  solution  becomes  purplish  or  claret-coloured. 

(h.)   Study   the    spectrum,    and   note   that  the  two  absorption- 


VI.]  THE   COLOURED   BLOOD    CORPUSCLES.  49 

bands  of  oxy-haemoglohin  are  replaced  by  one  absorption-band 
between  D  and  E,  not  so  deeply  shaded,  and  with  its  edges  less 
defined  (fig.  24,  4).  By  shaking  the  solution  very  vigorously  with 
air,  and  looking  at  once,  the  two  bands  may  be  caused  to  re- 
appear for  a  short  time.  Observe  the  absorption  of  the  light 
at  the  red  and  violet  ends  of  the  spectrum  according  to  the 
strength  of  the  fluid. 

(c.)  Dilute  the  solution,  and  observe  that  the  single  band  is 
not  resolved  into  two  bands,  but  gradually  fades  and  disappears. 

((/.)  To  a  similar  solution  of  oxy-hsemoglobin,  showing  two 
well-defined  bands,  add  Stokes's  fluid,  and  observe  the  single 
absorption-band  of  haemoglobin.  Shake  the  mixture  with  air  and 
the  two  bands  reappear. 

(e.)  Use  a  solution  of  oxy-haemoglobin  where  the  two  bands  can 
just  he  seen,  and  .reduce  it  with  either  ammonium  sulpliide  or 
Stokes's  fluid,  and  note  that,  perhaps,  no  absorption-band  of  hasmo- 
globin  is  to  be  seen,  or  only  the  faintest  shadow  of  one. 

(/.)  Compare  the  relative  strengths  of  the  solution  of  oxy- 
h£emoglobin  and  hsemoglobin.  The  latter  must  be  considerably 
stronger  to  give  its  characteristic  spectrum. 

Fig.  25  shows  the  amount  of  light  absorbed  by  solutions  of 
reduced  haemoglobin  (i  cm.  in  thickness),  and  of  various  strengths. 

Stokes's  Fluid. — Make  a  solution  of  ferrous  sulphate  ;  to  it  add 
ammonia  after  the  previous  addition  of  sufficient  tartaric  acid  to 
prevent  precipitation.  Add  about  three  parts  by  weight  of  tartaric 
acid  to  two  of  the  iron  salt.     Afake  it  fresh  when  required. 

8.  Reduction  of  HbOg  by  Putrefying  Bodies.— Fill  a  test-tube  with  a  dilute 
solution  of  oxy-hsemoglobin  or  blood,  add  a  drop  of  putrid  meat  infusion,  cork 
the  vessel  tightly  to  make  it  air-tight,  and  allow  it  to  stand.  I'he  oxy-hoemo- 
globin  is  reduced  to  hremoglobin,  the  colour  changes  to  i)urj)le-red,  and  the 
Huid  shows  the  spectrum  of  h;vmoglobin.  A  better  plan  is  to  seal  up  the 
blood  in  a  tube.  It  need  not  be  mixed  with  putrid  matter  in  order  to  observe 
after  a  time  the  reduction. 

9.  Haematinometer. — For  accurate  observation,  instead  of  a  test-tube  the 
blood  is  introduced  into  a  vessel  with  parallel  sides,  the  glass  plates  being 
exactly  i  cm.  apart  (fig.  31  D).     Study  this  instrument. 

10.  Hgematoscope  (fig.  27). — By  means  of  this  instrum.ent  the  depth  of  the 
stratum  of  fluid  to  be  investigated  can  be  varied,  and  the  variation  of  the 
spectrum,  with  the  strength  of  the  solution,  or  the  thickness  of  the  stratum 
through  which  the  light  passes,  at  once  determined.     Study  this  instrument. 

11.  III.  Carbonic  Oxide-Hsemoglobin. — Through  a  diluted  solu- 
tion of  oxy-haemoglobin  or  defibrinated  blood  pass  a  stream  of  car- 
bonic oxide — or  coal  gas — until  no  more  CO  is  absorbed.  Note  the 
florid  cherry-red  colour  of  the  blood. 

D 


50 


PRACTICAL  PHYSIOLOGY. 


[VI. 


Dilute  the  solution  in  a  test-tube  and  observe  its  spectrum, 
that  a  stronger  solution  is  required  than  with  HbOg,  to  show 
the  absorption-bands.  Two  absorp- 
tion-bands nearly  in  the  same  posi« 
tion  as  those  of  HbOg,  but  very 
sHghtly  nearer  the  violet  end  (fig.  24, 
3).  Make  a  map  of  the  spectrum 
and  bands. 

(b.)  The  bands  are  not  affected  by 
the  addition  of  a  reducing  agent, 
e.g. J  ammonium  sulphide  or  Stokes's 
fluid.  Add  these  fluids  to  two 
separate  test-tubes  of  the  solution 
of  COHb,  and  observe  that  the  two 
absorption  bands  are  not  affected 
thereby.  There  is  no  difference  on 
shaking  the  solution  with  air,  as  the 
compound  is  so  very  stable. 

(c.)  To  a  fresh  portion  of  the  solution  of 
carbonic  oxide  haemoglobin  add  a  10  per 
cent,  solution  of  caustic  soda  and  boil  = 
cinnabar-red  colour.  Compare  this  with 
a  solution  of  oxy-hsemoglobin  similarly 
treated.     The  latter  gives  a  brownish-red 


.27. — Haematoscope  of  Hermann,  F.        ,,.   y^.,    .  ri-i     j      •^•l  r 

Glass  plate ;  C.  Piston-like  tube,  {"• )  dilute  I  cc.  ot  blood  with  20  cc  of 
closed  by  a  glass  plate.  By  moving  water  +  20  cc.  of  caustic  soda  (sp.  gr.  i.  34). 
Cthespace^/^canbe  increased  or  if  the  blood  contains  CO,  the  fluid  first 
diminished,  and  the  thickness  of  the  -u^^^^^^  ^x^n.^     „j  „i„,  j  a   ,...«^„^4-i 

stratum  of  fluid  varied.  E.  Vessel  becomes  white  and  cloudy,  and  presently 
for  holding  surplus  fluid.  A.  Sup-  red.  When  allowed  to  stand,  flakes  form 
port.  and  settle  on  the  surface.     Normal  blood 

gives  a  dirty  brown  colouration, 
(e.)  Non-Eeduction  of  HbCO. — Repeat  the  above  experiment  (VL  8)  with 
carbonic  oxide  haemoglobin,  and  note  that  this  body  is  not  reduced  by  putre- 
faction.    Or  seal  up  the  blood  in  a  tube. 

12.  IV.  Acid-Hsematin. 

(a.)  To  diluted  defibrinated  blood  add  a  few  drops  of  glacial  acetic 
acid,  and  warm  gently,  when  the  mixture  becomes  brownish  owing 
to  the  formation  of  acid  haematin. 

{h.)  The  spectrum  shows  one  absorption-band  to  the  red  side  of 
D  near  C  (fig.  28,  5),  and  there  is  considerable  absorption  of  the 
blue  end  of  the  spectrum. 

(c.)  The  single  band  is  not  affected  by  ammonium  sulphide  or 
Stokes's  fluid.  JSTote  that  sulphur  is  precipitated  if  Am^S  is  used. 
If  the  fluid  is  made  alkaline  haemochromogen  is  formed. 

N,B. — If  acetic  acid  alone  be  used  to  effect  the  change,  observe 
that  only  one  absorption-band  is  seen. 


VI.] 


THE  COLOURED  BLOOD  CORPUSCLES 


V 


13.  Acid-Hgematin  in  Ethereal  Solution. 

(a,)  To  undiluted  defibrinated  blood  add  glacial  acetic  acid, 
which  makes  the  mixture  brown.  Extract  with  ether,  shake 
vigorously,  and  a  dark-brown  ethereal  solution  of  hsematin  is 
obtained.     Pour  it  off  and — 

{h.)  Observe  the  spectrum  of  this  solution — four  absorption 
bands  are  obtained.  The  one  in  the  red  between  C  and  D,  corre- 
sponding to  the  watery  acid-haematin  solution;  and  on  diluting 
further  with  ether  a  narrow  faint  one  near  D,  one  between  D  and 
P],  and  a  fourth  between  b  and  F  (fig.  28,  5).  The  last  three 
bands  are  seen  only  in  ethereal  solutions,  and  require  to  be  looked 
for  with  care. 

14.  V.  Alkali-Haematin. 

(a.)  To  diluted  blood  add  a  drop  or  two  of  solution  of  caustic 
potash,  and  warm  gently.  The  colour  changes  to  a  brownish-green, 
and  the  solution  is  dichroic.  Or  use  a  solution  of  acid-hsematin  ; 
neutralise  it  with  caustic  soda  until  there  is  a  precipitate  of 
haematin  ;  on  adding  more  soda  and  heating  gently,  the  precipitate 
is  re-dissolved,  and  alkali-hcematin  is  formed. 

(b.)  Sliake  (a.)  with  air  to  obtain  oxy-alkali-hsematin.  Observe 
its  spectrum,  one  absorption-band  just  to  the  red  side  of  the  D 
Hue.  It  is  much  nearer  D  than  that  of  acid  haematin  (fig.  28). 
Much  of  the  blue  end  of  the  spectrum  is  cut  off. 


Red.    Orange.  Yellow. 


Green. 


Blue. 


l.LMLLU.|ILlljlll.ljlni 

90  100  UO 

A    a     B    C  0  E  F 

FiO,  28.— Spectra  of  Derivatives  of  Haemoglobin.    5.  Ha;matin  in  ether  with  sulphuric 
acid  ;  6.  Hfematin  in  an  alkaline  solution ;  7.  Reduced  liscniatin. 

15.  Reduced  Alkali-Hsematin  or  Haemochromogen. 
{(I.)  Add  to  a  solution  of  alkali-hae.matin  a  few  drops  of  ammonium 
sulphide  and  warm  gently.     Note  the  change  of  colour  =  reduced 


52 


PRACTICAL   PHYSIOLOGY. 


[VI. 


alkali-hsematin,  Stokes's  reduced  hgematin  or  hsemochromogen, 

and  observe  its  spectrum ;  two  absorption-bands  between  D  and 
E,  as  with  HbO.,  and  HbCC),  but  they  are  nearer  the 
violet  end.  The  first  band  to  tlie  violet  side  of  the  D 
line  is  well  defined,  while  the  second  band,  still  nearer 
the  violet  end  (in  fact,  it  nearly  coincides  with  the 
E  line),  is  less  defined.  They  disappear  on  shaking 
vigorously  with  air,  and  reappear  on  standing,  pro- 
vided sufficient  ammonimn  sulphide  be  added. 

HaBmochromogen  and  Hsematin. — Seal  up  in  a  glass  tube 
a  solution  of  oxy-h:Temoglobin  with  caustic  soda.  Hoppe-Seyler 
recommends  the  following  method  but  it  is  unnecessary.     Ar- 

KEO  range  a  tube  as  in  fig,  29.  Place  some  hitmoglobin  solution 
in  A,  and  into  a  narrower  cup-shaped  glass  tube  (B),  with  a 
long  stem  place  some  NaHO,  and  place  B  inside  A,  as  shown 
in  the  figure.  Draw  out  the  end  of  tube  A  in  a  gas-flame,  and 
seal  it  in  the  flame.  Mix  the  two  solutions.  At  the  end  of 
three  weeks  break  ofl"  the  narrow  end  of  the  tube,  and  shed 
the  contents  upon  a  white  plate.     The  contents  consist  of  red 

^  hitmochromogen,  but  the  latter,  as  soon  as  it  is  exposed  to 
the  air,  becomes  brown,  and  is  converted  into  hsematin. 

16.  VI.  Methaemoglobin  (fig.  30). 
(a.)  To  a  medium  solution  of  oxy-hsemoglobin  add 
a   few  drops  of  a  freshly-prepared  strong  solution  of 
ferricyanide  of  potassium  (or  a  i  per  cent,  solution  of 
potassic    permanganate),    warm    gently,    observe    the 
change  of  colour,  and  examine  it  with  a  spectroscope. 
If  the  two  bands  of  oxy-haemoglobin  are  still  present, 
Fig.  29.  —  Appara-  allow   it   to    stand  for   some    time    and    examine 
tus    for   making  again.     If   they  persist,  carefully  add  more  ferri- 

Hsemochromogen.      &      .*  ,.,     ,,-^    ,        '   ,         i        i-  -».^   , 

cyanide  until  the  two  bands  disappear.  ^ote 
one  absorption-band  in  the  red  near  C,  nearly  in  the  same  posi- 
tion, but  nearer  D  than  the  band  of  acid  haematin;  the  violet 
end  of  the  spectrum  is   much  shaded.      Three  other   bands   are 


A  a  B  C 

.     40         50 


mi 


I 


70 


Eb 

80 


iiiiliinliiiilijllllllil||nllljll[llll 


F 

9p    ,  jqo       u 

liiulmiliiii 


m^miL 


A 


Fig.  30. — Spectnim  of  Methiemoglobin  in  Acid  and  Nential  Solutions. 

described,  tw-o  in  the  green,  and  one  in  the  blue,  especially  in 
dilute  solutions.  On  adding  ammonia  to  render  the  solution 
alkahne,  the  band  in  the  red  disappears,  and  is  replaced  by  a 
faint  band  near  D. 


J 


VI.]         THE  COLOURED  BLOOD  CORPUSCLES.         53 

Observe  the  many-banded  spectrum  of  a  solution  of  potassic 
permanganate. 

(b.)  To  an  alkaline  solution  of  methsemoglobin  add  ammonium 
suljDhide.  This  gives  the  spectrum  first  of  oxy-haemo.ulobin  and 
then  of  tuiemoglobin ;  and  on  shaking  with  air,  oxy-hamoglobin  is 
formed. 

(c.)  To  a  solution  of  oxy-hajmoglohin  add  a  crystal  or  two  of  potassic 
chlorate  ;  dissolve  it  with  the  aid  of  gentle  heat ;  after  a  short  time  the  spec- 
trum of  methsemoglobin  is  obtained. 

(fl.)  Action  of  Nitrites. — To  diluted  defibrinated  ox -blood,  or 
preferabl)'  that  of  a  dog,  add  a  few  drops  of  an  alcoholic  solution  of 
amyl  nitrite.  The  blood  immediately  assumes  a  chocolate  colour 
{Gamgee). 

(e.)  To  another  portion  of  diluted  blood  add  a  solution  of 
potassic  or  sodic  nitrite.     Observe  the  chocolate  colour. 

(/.)  To  portions  of  (d.)  and  (e.)  add  ammonia;  the  chocolate 
gives  place  to  a  red  colour. 

(<7.)  Observe  the  spectrum  of  (c?.)  and  {e.).  The  hand  in  the  red  is  distinct, 
and  is  best  seen  when  the  solution  is  of  such  a  strength  that  only  the  red  rays 
are  transmitted.  On  dilution,  other  bands  are  seen  in  the  green.  Add 
ammonia,  and  with  the  change  of  colour  described  m  (/.)  the  spectrum 
changes  as  desciibed  in  (a.).  Add  ammonium  sulphide  or  Stokes's  fluid,  the 
spectrum  of  reduced  haemoglobin  appears,  and  on  shaking  up  with  air,  the 
bands  of  oxy-hsemoglobin  appear. 

(h.)  Crystals  of  Methaemoglobin. — To  a  litre  of  concentrated  solution  of 
haemoglobin  add  3-4  cc.  of  a  concentrated  solution  of  fenicyanide  of  potassium 
and  also  a  quarter  of  a  litre  of  alcohol,  and  freeze  the  mixture.  After  two 
days,  brown  crystals  of  methaemoglobin  separate. 

(?'.)  To  a  few  cc,  of  defibrinated  blood  (rat,  guinea-pig),  add  an  equal 
number  of  drops  of  amyl  nitrite,  and  shake  the  mixture  vigorously  for  a 
minute  or  two  =  dark  chocolate  tint  of  methaemoglobin.  A  drop  of  this  fluid 
transferred  at  once  to  a  slide,  and  covered,  yields  crystals  of  methaemoglobin 
{Halliburton), 

17.  VII.  Hsematoporphyrin  (iron-free  h3?matin  CigHigNgO). 

(a.)  To  some  strong  sulphuric  acid  in  a  test-tube  add  a  few 
drops  of  undiluted  blood  (abou.t  5  drops  of  blood  to  8-10  cc. 
of  H.^SOJ  ;  mix  by  shaking,  when  a  clear  violet-red  cr  purple-red 
fluid  is  obtained. 

(6.)  Observe  two  absorption-bands,  one  close  to  and  on  the  red 
side  of  D,  and  a  second  half-way  between  D  and  K. 

(c.)  To  some  of  this  violet-red  solution  add  a  large  excess  of  water,  which 
throws  down  part  of  the  haimatoporj)hyrin  in  the  form  of  a  brown  precipitate, 
which  is  more  copious  if  tlie  acid  be  neutralised  with  an  alkali,  e.[/.,  caustic 
soda.  Dissolvfe  some  of  the  l)rowu  deposit  in  caustic  soda,  and  examine  it 
spectroscopically. 


54  PRACTICAL  PHYSIOLOGY.  [VI. 

(d.)  The  sjiectrura  shows  four  absorption-bands ;  a  faint  band  midway  be- 
tween C  and  D,  another  similar  one  between  D  and  E,  but  close  to  D  ;  a  third 
baud  near  E  ;  and  a  fourth  one,  darkest  of  all,  occupying  the  greater  part  of 
the  space  between  b  and  F,  but  nearer  the  former. 

In  all  cases  make  drawings  of  what  you  see,  and  compare  them  with  the 
table  of  characteristic  spectra  suspended  in  the  laboratory. 

18.  Picro-Carmine. — Its  spectrum  closely  resembles  that  of 
HbOg,  but  the  two  bands  are  much  nearer  the  violet  end,  one 
being  midway  between  D  and  E,  and  the  other  to  the  violet  side  of 
E.  The  bands  are  unchanged  on  addition  of  Am^S  or  Stokes's 
fluid.     The  solution  does  not  give  proteid  reactions. 


ADDITIONAL   EXEECISES. 

19.  Prolonged  Action  of  Methsemoglobin-forming  Reagents. — Allow 
KMn04,  KgFeCyg,  iodine,  amyl  or  potassium  nitrite  or  glycerine  to  act  on  HbO.j 
for  some  days  at  40^  C.  Methaemoglobin  is  first  formed,  then  haematin.  The 
latter  is  partially  precipitated.  Precipitate  may  be  washed  with  water  and 
dissolved  in  dilute  acid  or  alkali.  In  the  case  of  EgFeCye  the  solution  becomes 
cherry-red,  and  contains  cyan-haematin.  Its  spectrum  shows  one  broad  band, 
like  that  of  Hb,  between  D  and  E,  unchanged  on  shaking  with  air.  In  the  case 
of  amyl  nitrite  the  final  product  in  solution  has  a  spectrum  like  that  of  HbOg, 
unchanged  on  treatment  with  Am.S  (?  HbNO). 

HbOo  solution  or  dilute  blood  left  on  the  water-bath  at  40°  C.  for  some  days 
shows  first  a  partial  formation  of  methaemoglobin  and  later  becomes  Hb.  It 
does  not  become  converted  into  haematin  {J.  A.  Menzies). 

20.  Effect  of  Sodium  Fluoride. — To  BhO^  solution  or  diluted  blood,  add  a 
few  drops  of  i  per  cent.  NaFl  solution,  and  keep  at  40°  C.  until  the  colour 
changes  from  scarlet  to  a  rich  crimson.  Examine  the  spectrum.  In  addition 
to  traces  of  the  HbOo  bands,  there  will  be  seen  two  bands,  one  very  distinct  to 
the  red  side  of  D,  slightly  nearer  the  red  than  the  band  of  alkali-haematin,  the 
other,  not  easily  seen,  to  the  violet  side  of  E.  On  addition  of  Am^S,  the  spec- 
trum changes  first  to  that  of  HbO.2,  then  Hb. 

21.  Effect  of  Acids. —(a.)  To  15  cc.  dilute  blood  which  gives  a  well-marked 
spectrum  of  HbO.2,  add  5  drops  of  i  per  cent.  HCl  (or  other  acid).  The  colour 
changes  to  brown,  and  the  spectrum  to  that  of  acid  haematin.  Add  ammonia, 
the  spectrum  becomes  that  of  alkaline  methaemoglobin,  and,  on  addition  of 
Am.jS,  the  solution  changes  to  HbO,  then  Hb.  But,  if  Am^S  be  added  witli- 
out"  previous  addition  of  ammonia,  the  spectrum  becomes  that  of  haemo- 
chromogen  first  becoming  Hb  on  standing,  and  then  RhO^  appears  on  shaking 
the  solution  with  air, 

{b.)  Place  15  cc.  of  solution  of  pure  HbOa  with  well-marked  spectrum  in 
each  of  five  test-tubes.  To  these  add  i,  2,  5,  10,  and  15  drops  of  i  per  cent. 
HCl  respectively.  Place  all  on  a  water-bath  at  40°  C.  for  24  hours,  or  longer 
if  necessar}'.  In  some  of  the  tubes  a  precipitate  of  haematin  will  be  found,  and 
in  one  of  these  the  supernatant  fluid  will  be  colourless,  and  will  give  proteid 
reactions.     Decant  the  colourless  fluid,  and  collect  and  wash  with  water  the 


vil] 


WAVE-LENGTHS. 


55 


haematin  precipitate.  Dissolve  the  hiematin  in  water  containing  a  trace  of 
HCl.  It  will  give  the  spectrum  of  acid-hsematin.  To  one  portion  add  soma 
of  the  decanted  fluid  and  a  few  drops  AmoS,  to  another  add  Am^S  only.  In 
the  former  case  the  h;eniochroniogen  formed  will  gradually  become  partially 
converted  into  Hb  (prove  by  shaking  with  air  and  obtaining  spectrum  of 
HbOa),  ill  the  latter  case  the  hsemochromogen  will  remain  unaltered. 


LESSON  YII. 

WAVE-LENGTHS— DERIVATIVES  OP  HAEMO- 
GLOBIN—ESTIMATION  OF  H^gBMOGLOBIN. 


Spectroscopic  Determination  of  Wave-Lengths. — Use  Zeiss's 
spectroscope,  which  is  provided  with  an  illuminated  scale  for  this 
purpose. 

1.  W.L.  of  Absorption-Bands  of  Oxy-Hsemoglobin. 

(a.)  Arrange  the  apparatus   as   shown   in   fig.   31.      A   is   the 


Fig.  31. — Arrangement  of  the  Spectroscope  for  Detennlning  Wave-Lengtlis.     A.  Tele- 
scope; B.  Collimator  tube ;  C.  Scale  tube  ;  D.  Haematinometer. 

telescope   through   which   the   observer    looks    at    the    spectrum 
obtained  by  the  light  passing  through  B,  and  dispersed  by  the 


56  PRACTICAL  PHYSIOLOGY.  [VIL 

flint-glass  prism  in  the  centre  of  tlie  apparatus.  In  C  is  fixed 
a  scale  photographed  on  glass  and  illuminated  by  a  fan  tailed 
burner.     D  is  the  lifBmatinometer  containing  tlie  dilute  blood. 

(6.)  Throw  a  piece  of  black  velvet  over  the  prism ;  light  both 
lamps,  look  through  A;  adjust  tiie  sHt  in  B,  and  the  telescope 
in  A,  so  as  to  get  a  good  view  of  the  spectrum,  and  over  it  the 
image  of  the  scale.  D  is  supposed  not  to  be  in  position  at  first. 
On  platinum  wire,  burn  common  salt  in  the  flame  to  get  the  yellow 
sodium  line  D.  Adjust  the  scale  so  that  this  line  corresponds  to 
the  figures  58.9  on  the  scale,  and  fix  the  spectroscope  tubes  (A 
and  C)  in  this  position  ;  the  scale  is  now  accurately  adjusted  for  all 
other  parts  of  the  spectrum. 

"  The  numbers  on  the  scale  indicate  wave-lengths  expressed  in 
one  hundred  thousandths  of  a  milUmetre,  and  each  division  indi- 
cates a  difference  in  wave-length  equal  to  one  hundred  thousandth 
of  a  millimetre  "  {Gamgee.) 

Thus,  Fraunhofer's  line,  D,  which  corresponds  to  division  58.9 
of  the  scale,  has  a  wave-length  of  589  millionths  of  a  milhmetre. 
The  wave-lengths  of  Fraunhofer's  lines  are  : — A=  760.4,  B  =  687.4, 
0  =  656.7,  0  =  589.4,  E=527.3,F  =  486.5. 

(c.)  Using  one  of  the  blank  maps  supplied  with  Zeiss's  spectro- 
scope— the  maps  correspond  to  the  scale  seen  in  the  spectroscope — 
fill  in,  in  wave-lengths,  the  position  of  Fraunhofer's  lines  B  to  F. 

(d.)  Use  a  dilute  solution  of  blood  or  haemoglobin  —  i  part  in 
1000  of  water  is  best — and  place  it  in  the  hsematinometer,  D, 
which  is  placed  in  position  between  the  flame  and  the  spectroscope, 
as  shown  in  fig.  31.  The  distance  between  the  parallel  faces  of  D 
is  I  cm.  The  spectrum  shows  the  two  absorption-bands  of  oxy- 
hcEmoglobin  between  D  and  E.  The  narrower,  sharper,  and  blacker 
band  near  D  has  its  centre  corresponding  with  the  W.L.  579,  and 
it  may  conveniently  be  expressed  by  the  letter  a  of  the  oxy 
hsemoglobin  spectrum. 

The  other  absorption-band  near  E,  and  conveniently  designated 
)8,  is  broader,  not  so  dark,  and  has  less  sharply  defined  edges  than 
a.  Its  centre  corresponds  to  the  W.L,  543.8.  Notice  that  the 
other  parts  of  the  spectrum  are  seen,  there  being  only  slight 
cutting  off  of  the  red,  and  a  slightly  greater  absorption  of  the  violet 
end. 

(e.)  Work  with  a  stronger  solution  of  blood,  and  observe  how 
the  two  bands  become  fused  into  one,  while  more 'and  more  of  the 
red  and  violet  ends  of  the  spectrum  are  absorbed  as  the  solution  is 
made  stronger,  until  finally  only  a  little  red  Hght  is  transmitted. 

2.  W.L.  of  Absorption-Band  of  Reduced  Hb. 

(a.)  Adjust  the  apparatus  as  before,  but  reduce  the  oxy-haemo- 


VII.] 


WAVE-LENGTHS. 


57 


globin  solution  with  Stokes's  fluid — noticing  the  change  of  the 
colour  to  that  of  purplish  or  claret — until  a  solution  is  obtained 
which  gives  the  single  characteristic  absorption-band  of  reduced 
Hb.  Tliis  is  usually  obtained  with  a  solution  of  Hb  of  about  0.2 
per  cent. 

(b.)  Observe  the  single  absorption-band  less  deeply  shaded,  and 
with  less  defined  edges  between  D  and  E,  conveniently  designated 
by  the  letter  a.  It  extends  between  W.L.  595  and  538,  and  is 
not  quite  intermediate  between  D  and  E ;  is  blackest  opposite 
W.L.  550,  so  that  it  lies  nearer  D  than  E.  Both  ends  of  the 
spectrum  are  more  absorbed  than  with  a  solution  of  oxy-haemo- 
globin  of  the  same  strength.  On  further  dilution  of  the  solution, 
the  band  does  not  resolve  itself  into  two  bands,  but  simply 
diminishes  in  width  and  intensity  (fig.  32,  5). 


A  <t 

:f  0 

>       66       V 

60 
III. 

.  .  .  r  . 

40 
,           .           .             1              1 

i| 

1  i 

^1 

1 1 

I^^^^^^^^^H 

^H 

■■■■^■I 

^■HT 

1            1  1 

H^HI^^^H^^^I 

1            1  1 

5^g 

"E3 

^■Hn 

II 

{iiHHJIHH 

J035J0  ^ejJ 

III  1  1  1  1  1  1 

"^'^1 

'i.' 

■       '       •      .'6       ' 

'        '        Jo 

1 

FlQ.  32.— The  Spectra  of  Oxy-Haemoglobin  (i,  2,  3,  4),  1=0.1,  2=0.2,  3  =  . 37,  4  =  . 8  per  cent, 
of  Oxy-Haemoglobiu,  Hjemoglobin  (5),  and  Carbonic  Oxide  Haemoglobin  (6).  Wave- 
lengths added.  The  numbers  attached  to  the  scale  indicate  wave-lengths  expressed 
in  loo.oooths  of  a  millimetre. 


3.  W.L.  of  the  Spectrum  of  Carbonic  Oxide  Hasmoglobin. 

(a.)  Use  a  dilute  solution  of  carbonic  oxide  haemoglobin  of  such 

strength  as  to  give  the  two  characteristic  absorption-bands. 

(h.)  Observe  the  two  bands,  a  and  f3,  like  those  of  HbO.^,  but 
both  are  very  slightly  more  towards  the  violet  end  of  the  spectrum. 
a  extends  from  about  W.L.  587  to  564,  and  f3  from  547  to  529. 

(c.)  No  reduction  is  obtained  by  reducing  agents  (fig.  32,  6), 


S8 


PRACTICAL  PHYSIOLOGT. 


[VII. 


4.  Preparation  of  HaBinatin  (C32H33N404Fe). 

{a.)  Make  defibriuated  blood  into  a  paste  with  potassic  carbonate  and  dry 
it  on  a  water-bath.  Place  the  paste  in  a  flask,  add  4  volumes  of  alcohol,  and 
boil  on  a  water-bath.  Filter,  and  an  alkaline  brown  solution  of  hiTematin  is 
obtained.  Re-extract  the  residue  several  times  with  boiling  alcohol,  and  mix 
the  alcoholic  extracts.     The  solution  is  dichroic. 

lb.)  Acidify  the  alkaline  filtrate  of  (a.)  with  dilute  sulphuric  acid,  filter, 
and  keep  the  filtrate.  Observe  the  spectrum  of  acid  h^ematin  in  the  filtrate 
(figs.  28,  5,  and  33,  5). 


Fig.  33. — Spectra  of  some  of  the  Derivatives  of  Haemoplobin.  i.  Haematin  in  alkaline 
solution;  2.  The  same,  but  more  concentrated  ;  3.  Haemochromogen  ;  4.  Methsemo- 
globin  ;  5.  Acid  hsematin  (acetic  acid) ;  6.  Acid  hsematiu  in  ethereal  solution. 


(c.)  Add  excess  of  ammonia  to  the  acid  filtrate  o({b.\  and  filter  off  the  pre- 
cipitate, keep  the  filtrate,  and  observe  that  it  is  dichroic.  Observe  the 
spectrum  of  alkali  htematin  in  the  filtrate  (fig.  28,  6). 

(d.)  Evaporate  the  filtrate  from  (f.)  to  dryness  on  a  water-bath.  Extract 
the  residue  with  boiling  water.  The  black  residue  is  washed  on  a  filter  with 
distilled  water,  alcohol,  and  ether,  and  dried  in  a  hot  chamber  at  120°  C. 
This  is  nearly  pure  haematin. 

(«.)  It  is  convenient  to  keep  in  stock  hrematin  prepared  as  follows  :— Ex- 
tract defibriuated  blood  or  blood-clot  ''ox  or  sheep)  with  rectified  spirit  con- 
taining pure  sulphuric  acid  (i  :  20.)  Filter  ;  the  solution  gives  the  spectrum 
of  acid  hrematin.  Add  an  equal  volume  of  water  and  then  chloroform.  The 
chloroform  becomes  brown,  and  there  is  a  precijjitate  of  proteids.  Separate 
the  chloroform  extract,  wash  it  with  water  to  remove  the  acid.  Separate  the 
chloroform,  and  allow  it  to  evaporate.  The  dark  brown  residue  is  impure 
ha-matin.  When  dissolved  in  alcohol  and  caustic  soda  it  gives  the  spectrum 
of  alkali  hcematin,  and  on  adding  ammonium  sulphide  that  of  haemochromogen. 
If  it  is  dissolved  in  H0SO4,  and  filtered,  through  asbestos,  the  red  filtrate  gives 
the  spectrum  of  hajmato-porphyrin  {MacMunn). 


VII.]  ESTIMATION    OF  HEMOGLOBIN.  59 

5.  Haemin  Crystals-. — Place  some  powdered  dried  blood  on  a 
glass  slide,  or  smear  some  blood  on  a  slide,  allow  it  to  dry,  add  a 
crystal  of  sodium  chloride,  and  a  few 
drops  of  glacial  acetic  acid.  Cover 
with  a  cover-glass,  and  heat  until 
bubbles  of  gas  are  given  off.  After 
cooling,  brown  or  black  rhombic 
crystals  of  htemin  are  seen  with  a 
microscope  (fig.  34).  To  preserve 
them    irrigate    with   water,    dry   and         ^  „     .   p,.„,x„,, 

,   .      °  1,1  Fia.  34.— Hpcniui  Crystals. 

mount  m  Canada  balsam. 

6.  Detection  of  Blood-Stains. — Use  a  piece  of  rag  stained  with 
blood. 

(a.)  Moisten  a  part  of  the  stain  with  glycerine,  and  after  a  time 
express  the  liquor,'  and  observe  it  microscopically  for  blood-cor- 
puscles. 

{b.)  Tie  a  small  piece  of  the  stained  cloth  to  a  thread,  place  the 
cloth  in  a  test-tube  with  a  few  drops  of  distilled  water,  and  leave 
it  until  the  colouring-matter  is  extracted.  Withdraw  the  cloth  by 
means  of  the  thread.  Observe  the  coloured  fluid  spectroscopi- 
cally. 

{('.)  Boil  some  of  the  extract  with  hydrochloric  acid,  and  add 
potassic  ferrocyanide ;  a  blue  colour  indicates  the  presence  of  iron. 

{d.)  Use  the  stain  for  the  hsemin  test,  doing  the  test  in  a  watch- 
glass. 

7.  The  Haemoglobinometer  of  Gowers  is  used  for  the  clinical 
estimation  of  haemoglobin  (fig.  35).  The  tint  of  the  dilution  of  a 
given  volume  of  blood  with  distilled  water  is  taken  as  the  index  of 
the  amount  of  haemoglobin.  The  colofir  of  a  dilution  of  average 
normal  blood  (one  hundred  times)  is  taken  as  the  standard.  The 
quantity  of  haemoglobin  is  indicated  by  the  amount  of  distilled 
water  needed  to  obtain  the  tint  with  the  same  volume  of  blood 
under  examination  as  was  taken  of  the  standard.  On  account  of 
the  instability  of  a  standard  dilution  of  blood,  tinted  glycerin 
jelly  is  employed  instead.  The  apparatus  consists  of  two  glass 
tubes  of  exactly  the  same  size.  One  contains  (D)  a  standard  of 
the  tint  of  a  dilution  of  20  c.mm.  of  blood,  in  2  cc.  of  water  (i  in 
100).  The  second  tube  (C)  is  graduated,  100°  =  2  cc.  (100  times 
20  c.mm.). 

(a.)  Place  a  few  drops  of  distilled  water  in  the  bottom  of  the 
graduated  tube  (C). 

(/>.)  Puncture  the  skin  at  the  root  of  the  nail  with  the  shielded 
lancet  (F),  and  with  the  pipette  (13)  suck  up  20  c.mm.  of  the  blood, 
and  eject  it  into  the  distilled  water,  and  rapidly  mix  them. 


6o 


PRACTICAL   PHYSIOLOGY. 


[VII. 


('•.)  Distilled  water  is  then  added  drop  by  drop  (from  the  pipette 
stopper  of  a  bottle  (A)  suppUed  for  that  purpose)  until  the  tint  of 
the  dilution  is  the  same  as  that  of  the  standard.  The  amount  of 
water  which  has  been  added  {i.e.,  the  degree  of  dilution)  indicates 
the  amount  of  haemoglobin. 

"  Since  average  normal  blood  yields  the  tint  of  the  standard  at 
1 00°  of  dilution,  the  number  of  degrees  of  dilution  necessary  to 


Fia.  35.— -4.  Pipette  bottle  for  distilled  water  ;  B.  Capillary  pipette ;   C.  Graduated  tube. 
D.  Tube  with  standard  dilution  ;  F.  Lancet  for  pricking  the  finger. 

obtain  the  same  tint  with  a  given  specimen  of  blood  is  the  per- 
centage proportion  of  the  haemoglobin  contained  in  it,  compared  to 
the  normal.  For  instance,  the  20  c.mm.  of  blood  from  a  patient 
with  anaemia  gave  the  standard  tint  of  30"  of  dilution.  Hence  it 
contained  only  30  per  cent,  of  the  normal  quantity  of  haemoglobin. 
By  ascertaining  with  the  haemacytometer  the  corpuscular  richness  of 
the  blood  we  are  able  to  compare  the  two.  A  fraction  of  which 
the  numerator  is  the  percentage  of  haemoglobin,  and  the  denomina- 
tor the  percentage  of  corpuscles,  gives  at  once  the  average  value  per 
corpuscle.  Thus  the  blood  mentioned  above  containing  30  per  cent, 
of  haemoglobin  contained  60  per  cent,  of  corpuscles;  hence  the 
average  value  of  each  corpuscle  was  f^  or  half  of  the  normal. 
Variations  in  the  amount  of  haemoglobin  may  be  recorded  on  the 
same  chart  as  that  employed  for  the  corpuscles." 

"  In  using  the  instrument,  the  tint  may  be  estimated  by  holding 
the  tubes  between  the  eye  and  the  window,  or  by  placing  a  piece 
of  white  paper  behind  the  tubes ;  the  former  is  perhaps  the  best 


VII.] 


ESTIMATION   OF   HAEMOGLOBIN. 


6i 


In  practice  it  will  be  found  that,  during  6  or  8  degrees  of  dilution, 
it  is  difficult  to  distinguish  a  difterence  between  the  tint  of  the 
tubes.  It  is  therefore  necessary  to  note  the  degree  at  which  the 
colour  of  the  dilution  ceases  to  be  deeper  than  the  standard,  and 
also  that  at  which  it  is  distinctly  paler.  The  degree  midway 
between  these  two  will  represent  the  haemoglobin  percentage." 


ADDITIONAL  EXERCISES. 


8i  Fleischl's  Haemometer.— This  apparatus  (fig.  36)  consists  of  a  horse-shoe 
stand  with  a  pillar  bearing  a  reflecting  surface  (S)  and  a  platform.  Under 
the  table  or  platform  is  a  slot  carrying  a  glass  wedge  stained  red  (K),  and 
moved  by  a  wheel  (R).     On  the  platform  (M)  is  a  small  cylindrical  vessel  (G), 


Fleischl's  Haemoraeter. 


divided  into  two  compartments  (a  and  a')  by  a  vertical  septum.  In  one 
compartment  is  placed  pure  water,  and  in  the  other  the  blood  to  be  investi- 
gated. A  scale  (P)  on  the  slot  of  the  instrument  enables  one  to  read  off 
directly  the  percentage  of  h?emoglobin.  .,.,..„, 

{a.)  Fill  with  a  pipette  the  compartment  (a')  over  the  wedge  with  distilled 
water,  and  see  that  the  surface  of  the  water  is  quite  level  with  the  top  of  the 
cylinder.  Fill  the  other  compartment  (a),  that  for  the  blood,  about  one- 
quarter  with  distilled  water. 


62 


PRACTICAL  PHYSIOLOGY. 


[VIL 


{h.)  Prick  the  finger  as  in  7  with  the  instrument  supplied  for  the  purpose. 
Fill  the  short  automatic  capillary  japette  tube  with  blood.  Its  capacity  ia 
6.5  c.mm.  In  filling  the  tube,  hold  it  horizontally.  See  that  no  blood 
adheres  to  the  surface  of  the  tube.  This  can  be  done  by  having  the  pipette 
slightly  greasy  on  the  outer  surface. 

(c.)  Dissolve  the  blood  obtained  in  {b.)  in  the  water  of  the  blood-compart- 
ment {(i),  washing  out  every  trace  of  blood  from  the  pipette.  Mix  the  blood 
and  water  thoroughly.  Clean  the  pipette.  Then  fill  the  blood  compartment 
exactly  to  the  surface  with  distilled  water,  seeing  that  its  surface  also  is  per- 
fectly level. 

{(l.)  Arrange  a  candle  in  front  of  the  reflector  (S) — which  is  white,  and  with 
a  smooth  matt  surface  made  of  plaster-of-Paris— so  as  to  throw  a  beam  of  light 
vertically  through  both  compartments.  Look  down  vertically  upon  both 
compartments,  and  move  the  wedge  of  glass  by  the  milled  head  (T)  until  the 
colour  in  the  two  compartments  is  identical.  Read  ofiF  the  scale,  which  is  so 
constructed  as  to  give  the  percentage  of  hemoglobin. 

9.  Bizzozero's  Chromo-Cytometer. — The  chief  part  of  the  instrument  con- 
sists of  two  tubes  (fig.  37,  ab,  cd),  working  one  within  the  other,  and  closed 
at  the  same  end  by  glass  discs,  while  the  other  ends  are  open.     The  one  tube 

can  be  completely  screwed  into 


the  other,  so  that  both  gh 
touch.  Connected  with  the  outer 
tube  is  a  small  open  reservoir  (r), 
firom  which  fluid  can  pass  into 
the  variable  space  between  the 
two  glass  plates  at  the  ends  of 
the  tubes.  By  rotating  the  inner 
tube,  the  space  between  the  two 
glass  plates  can  be  increased  or 
diminished,  on  the  principle  of 
Hermann's  hsematoscope,  and 
the  screw  is  so  graduated  as  to 
indicate  the  distance  between 
the  two  plates,  i.e.,  the  thick- 
ness of  fluid  between  them.  Each 
complete  turn  of  the  screw  =  0.5 
mm.,  and  the  subdivisions  on  it 
are  so  marked — 25  to  one  turn 
(index    fig.    37    w?)— that   each 

subdivision    of    the  index  =^ 

37.— General  View  of  the  Chromo-Cytometer.  wv.^.,    fi,..   ,-t,t,^^ 

oSandcd.  Two  tubes,  the  one  fits  inside  the  =0-02  mm.  When  the  inner 
other ;  r.  Reservoir  coramunicatincr  with  the  tube  is  screwed  home  and  touches 
space  between  c  and  b  when  cd  is  screwed  into  the  glass  disc  in  the  outer  tube, 
ab ;  er.  Milled-head  and  index  sci\le  to  the  left  -1  in^PY  <;tiiiiH<;  at  n  on  thp  «?fvilp 
of  it,  for  the  tinted  glass ;  m.  Handle.  the  index  stands  at  o  on  the  scale. 

If  the  instrument  is  to  be  used 
merely  as  a  cytometer,  these  parts  suffice  ;  but  if  it  is  to  be  used  as  a  chromo- 
meter,  the  coloured  glass  must  be  used.  The  instrument  is  also  provided 
with  small  glass  thimbles  with  flat  bottoms,  containing  2  and  4  cc.  respectively; 
a  pipette  graduated  to  hold  ^  and  i  cc,  and  another  pipette  for  10  and  20 
c.mm.,  the  latter  provided  with  an  india-rubber  tube,  to  enable  the  fluid 
to  be  sucked  up  readily  ;  a  bottle  to  hold  the  saline  solution,  and  a  glass 
stirrer. 

Method  of  Using  the  Instrument  as  a  Cytometer. — i.  By  means  of  the 
pipette  place  0*5  cc.  in  normal  saline  solution  in  a  glass  thimble. 


VII.] 


ESTIMATION  OF  HEMOGLOBIN. 


63 


2.  With  a  lancette  or  needle  puncture  the  skin  of  the  finger  at  the  edge  ol 
the  nail. 

3.  With  the  j)ipette  suck  up  exactly  10  c.mm.  of  blood.  Mix  this  blood  with 
the  .5  c.cm.  saline  solution,  and  suck  part  ol  the  latter  several  times  into  the 
capillary  tube,  so  as  to  re- 
move every  trace  of  blood 
from  the  pipette.  Mix  the 
fluids  thoroughly.  Care- 
fully cleanse  the  pipette 
with  water. 

4.  Pour  the  mixture  into 
the  reservoir  (r)  of  the  in- 
strument. Gradually  rotate 
the  inner  tube,  and  as  the 
two  glass  discs  separate, 
the  fluid  passes  into  the 
space  between  them. 

5.  In  a  dark  room  light 
a  stearin  candle,  place  it  at 
a  distance  of  i^  metres,  and,  taking  the  instrument  in  the  left  hand,  bring 
the  open  end  of  the  tubes  to  the  right  eye.  With  the  right  hand  rotate  the 
inner  tube  to  vary  the  thickness  of  the  column  of  fluid,  and  so  adjust  it 
until  the  outlines  of  the  upper  three-fourths  of  the  flame  can  be  distinctly 
seen  through  the  stratum  of  fluid.  Vary  the  position  of  the  inner  screw  so 
as  to  determine  accurately  when  this  occurs.  Read  off  on  the  scale  the 
thickness  of  the  stratum  of  fluid. 


.  ^8.— Showing  how  ed  fits  Into  ab.  zz.  Plates  of  glasi 
closing  the  ends  of  ah  and  cd;  other  letters  as  in 
fig.  37- 


Graduation  of  the  Instrument  as  a  Cytometer. — In  this  instrument  the 
graduation  is  obtained  from  the  thickness  of  the  layer  of  blood  itself,  and  the 
amount  of  haemoglobin  is  calculated  directly  from  the  thickness  of  the  layer 
of  blood  which  is  necessary  to  obtain  a  certain  optical  effect,  viz.,  through  the 
layer  of  blood-corpuscles  to  see  the  outlines  of  a  candle-flame  placed  at  a 
certain  distance. 

From  a  number  of  investigations  it  appears  that  in  healthy  blood  the  out- 
lines of  the  flame  of  a  candle  are  distinctly  seen  through  a  layer  of  the  mixture 

of  blood  —  mm.  in  thickness. 
100 

Let  the  number  no  correspond  to  i,  or  to  100  parts  of  haemoglobin  ;  then 
it  is  easy  to  calculate  the  relative  value  of  the  subdivisions  of  the  scale  on  the 
tube  of  the  instrument.  Let  g  =  the  degree  of  the  scale  for  normal  blood  ; 
g\  that  for  the  blood  being  investigated  ;  e,  amount  of  haemoglobin  in  the 
former  ;  and  e',  the  amount  sought  for  in  the  latter. 

Assuming  that  the  product  of  the  quantity  ut  haemoglobin  and  the  thickness 
of  the  stratum  of  blood  is  constant,  so  that 


Then  we  have 


eg='e'g^. 


Let  us  assume  that  the  blood  investigated  gave  the  nmnber  180;  then 
using  the  above  data,  we  have : — 


looxiio    11,000 


180 


180 


.61.1. 


64  PRACTICAL  PHYSIOLOGY.  [VII 

The  blood,  therefore,  contains  61.1  haemoglobin.     The  following  table  givea 
the  proportion  of  haemoglobin,  the  normal  amount  of  haemoglobin  being  taken 


as=ioo:— 

Cytometer  Scale. 

Haeraoglobui 

Cytoineter  Scale. 

Hsemoglobin. 

IIO 

.       lOO.O 

170 

.       64.7 

120 

91.6 

180 

.        61. 1 

130 

.        84.6 

190 

.       57-9 

140 

.        78.5 

2CX> 

.      5S.O 

150 

.        73.3 

210 

.      52.4 

160 

.        68.7 

220 

50.0 

Using  the  Instrument   as  a  Chromometer.- 

-The  blood 

is  mixed  with  a 

known  volume  of  water,  whereby  the  haemoglobin  is  dissolved  out  of  the  red 
corpuscles  and  the  fluid  becomes  transparent.  The  quantity  of  haemoglobin  is 
calculated  from  the  thickness  of  the  stratum  of  fluid  required  to  correspond 
exactly  to  the  colour-intensity  of  a  coloured  glass  accompanying  the  instru- 
ment. The  latter  is  coloured  of  a  tint  similar  to  a  solution  of  haemoglobin, 
and  is  fixed  to  the  instrument  by  means  of  a  suitable  brass  fixture. 

1.  Fix  the  coloured  glass  with  its  brass  frame  in  the  instrument. 

2.  Mix  10  c.mm.  blood  with  .5  cc.  distilled  water.  In  a  few  seconds  a  trans- 
parent solution  of  haemoglobin  is  obtained. 

3.  Pour  this  solution  into  the  reservoir  (r),  and  rotate  the  inner  tube  so 
that  the  fluid  passes  between  the  two  glasses.  Direct  the  instrument  towards 
a  white  light  or  the  sky,  not  towards  the  sun,  and  compare  the  colour  of  the 
solution  with  the  standard  coloured  glass,  a  procedure  which  is  facilitated  by 
placing  a  milky  glass  between  the  source  of  light  and  the  layer  of  blood,  so  as 
to  obtain  diffuse  white  light.  When  the  two  colours  appear  to  have  as  near 
as  possible  the  same  intensity,  read  off"  on  the  scale  the  thickness  of  the  layer 
of  blood,  and  from  this,  by  means  of  the  accompanying  table,  ascertain  the 
corresponding  amount  of  haemoglobin. 

This  is  done  in  the  same  way  as  tor  the  cytometer,  but  the  graduation  is 
difi'erent,  as  in  the  one  case  we  have  to  do  with  a  candle-flame,  and  in  the 
other  with  a  coloured  glass. 

In  very  pronounced  cases  of  anaemia,  even  with  a  layer  of  blood  6  mm.  in 
thickness,  owing  to  the  limits  of  the  instrument,  the  intensity  of  the  mixture 
of  blood  may  be  less  than  that  of  the  coloured  glass.  In  such  a  case, 
instead  of  10  c.mm.  of  blood,  use  20  c.mm. 

Graduation  of  the  Cliromometer. — As  the  coloured  glass  has  not  absolutely 
the  same  intensity  of  colour  in  all  chromometers,  one  must  first  of  all  estimate 
the  colour-intensity  of  the  glass  itself.  This  is  most  easily  done  by  ascertain- 
ing in  a  given  specimen  of  blood  what  degree  ot  the  chromometer  corresponds 
to  the  scale  of  the  cytometer  of  the  same  blood. 

Suppose  that  a  specimen  of  blood  by  means  of  the  cytometer  gave  no,  and 
by  the  chromometer  140  ;  the  number  1 10  of  the  cytometer  =  100  haemoglobin, 
so  that  the  chromometer  number  140  must  also  be  =  100.  "With  the  aid  of 
the  formula  (p.  63)  a  similar  table  can  be  constructed  for  the  chromometer. 
Suppose  the  blood  investigated  =  280 ;  then  by  the  aid  >f  the  formula  and 
the  data  from  normal  blood  we  have— 

14,000^^ 


280  280 

This  blood,  therefore,  contains  50  parts  of  haemoglobin. 

Example. — Blood  gives  130  with  the  cytometer  and  190  with  the  chromo 
meter  ;  what  is  the  initial  number  of  the  chromometer  graduation  correspond 
ing  to  icx)  parts  of  haemoglobin ! 


VII.]  ESTIMATION   OF   HAEMOGLOBIN.  65 

If  130  Ccytorneter)  corresponds  to  190  (cliromometer)  then  no  cytometer 
(?.e,,  graduation  corresponding  to  100  parts  of  hasmoglobiu)  corresponds  to  it 
chromometer  graduation  : 

190.  no       20,900       ,^    ^ 

no  :  190  =  1 10  :  a; .  .  a;  =  —2 =  — 'y —  =  100.7. 

•"  130  130 

Blood  containing  100  ])arts  luTemoglobin  will  correspond  to  160  of  the  chromo- 
meter scale,  and  beginning  with  this  number  as  a  basis,  with  the  aid  of  our 
formula  it  is  easy  to  cojistruct  a  table  showing  the  relation. 

Whilst  the  value  of  the  cytometer  scale  remains  the  same  for  every  instru- 
ment, the  chromometer  scale  varies  with  each  instrument,  as  the  colour- 
intensity  of  the  glass  is  not  necessarily  the  same  in  all.  But  it  is  easy  to 
construct  a  scale  for  each  instrument  by  investigating  a  specimen  of  blood 
and  comparing  it  with  the  cytometer  graduation  as  indicated  in  the  foregoing 
paragraph. 

Frecautiaiis  to  he  Observed  in  Using  the  Instrument. — The  exact  quantity  of 
the  several  fluids  must  be  carefully  measured  ;  evaporation  must  be  prevented 
by  covering  the  blood-mixture.  Further,  do  not  look  at  the  fluid  too  long  at 
a  time,  as  the  eye  becomes  rapidly  fatigued.  Further,  the  operation  must  be 
carried  out  not  too  slowly,  as  the  saline  solution  only  retards  the  coagulation 
of  the  blood,  and  does  not  arrest  it. 

In  cases  of  leukaemia,  where  there  is  a  large  number  of  white  corjmscles 
rendering  the  mixed  fluid  opaque,  the  corpuscles  may  be  made  to  disappear  by 
adding  a  drop  of  a  very  dilute  caustic  potash.  If  the  opacity  does  not  disappear 
by  the  addition  of  this  substance,  then  the  o])acity  is  due  to  the  presence  of 
fatty  granules  in  the  blood,  so  that  by  this  means  we  can  distinguish  lipttmia 
from  leukaemia. 

Bizzozero  claims  that  when  the  instrument  is  used  as  a  cytometer  the  mean 
error  is  not  greater  than  o.  3  per  cent 

10.  Preparation  of  Hsemoglobin  {clog^s  or  Iwrse's  blood). — Centrifugalise 
filtered  fresh  defibrinated  dog's  blood,  and  when  the  corpuscles  have  subsided 
pour  off"  the  clear  serum.  Mix  the  corpuscles  with  .5-2  per  cent,  solution  of 
NaCl,  and  centrifugalise  again.  Repeat  the  process  until  the  washings  con- 
tain only  a  trace  of  proteid,  or  begin  to  be  tinged  red  from  the  solution  of  the 
blood-corpuscles. 

Mix  the  magma  of  corpuscles  with  2-3  volumes  of  water  saturated  with 
acid-free  ether.  The  corpuscles  swell  up,  become  almost  invisible,  and  the 
solution  becomes  clear.  "With  the  utmost  care  add,  stirring  all  the  time,  i  per 
cent,  solution  of  acid  sodic  sulphate  until  the  blood  appears  turbid  like  fresh 
blood.  The  stromata  of  the  corpuscles  are  thereby  caused  to  shrivel,  and  when 
they  are  centrifugalised  for  a  long  time,  they  run  together,  and  can  thus  be 
separated.  Pour  ofl*  the  clear  fluid,  cool  it  to  0°,  add  one-fourth  of  its  volume 
of  pure  alcohol  previously  cooled  to  o"  or  lower.  Shake  up  the  whole,  and  let 
it  stand  for  twenty-four  hours  at  5°-i5''.  As  a  rule,  the  whole  passes  into  a 
glittering  crystalline  mass.  Place  it  in  a  filter  cooled  to  0°,  and  wash  it  with 
ice-cold  25  per  cent,  alcohol.  Redissolve  the  crystals  in  a  small  quantity 
of  water,  and  recrystallise  with  alcohol  as  before.  The  crystals  are  spread  on 
plates  of  porous  porcelain,  and  dried  in  a  vacuum  over  sulphuric  acid. 

11.  Amount  of  Hsemoglobin  in  Blood— Colorimetric  Method  (Hoppe- 
Seyler's  method). — A  standard  solution  of  pure  haemoglobin  diluted  to  a 
known  strength  is  used,  and  with  this  is  compared  the  tint  of  the  blood 
diluted  with  a  known  volume  of  distilled  water. 

(a.)  A  standard  solution  of  hsemoglobin  of  known  strength  is  supplied  (sMj^ra), 

B 


66 


PRACTICAL  PHYSIOLOGY. 


[VII. 


(b.)  Spread  a  sheet  of  white  paper  on  a  table  in  a  good  light  opposite  a 
window,  and  on  it  place  two  ha-matinometers  side  by  side  (fig.  31,  D).  See 
that  they  arc  water-tight.  If  not,  anoint  the  edges  of  the  glass  plates  with 
vaseline  to  make  them  water-tight. 

(c.)  Take  10  cc.  of  the  standard  solution  of  huemoglobin  and  dilute  it  with 
50  cc.  of  water,  and  j)lace  it  in  one  of  the  haematinometers. 

{d.)  Weigh  5  grams  of  the  blood  to  be  investigated,  and  dilute  it  with 
water  exactly  to  100  cc. 

{e.)  Place  10  cc.  of  this  desper  tinted  blood  {d.)  into  the  second  haematino- 
meter. 

(/. )  Fill  an  accurately  graduated  burette  with  distilled  water,  place  it  over 
the  second  ha^matinometer  {e. ),  and  dilute  the  blood  in  it  until  it  has  precisely 
the  same  tint  as  the  standard  solution  in  the  other  hfematinometer.  Note  the 
amount  of  water  added.  The  two  solutions  must  now  contain  the  same 
amount  ofhaenjoglobin. 

'EtXB.m.T^le  {HuppeSeyler). — 20.186  grams  of  defibrinated  blood  were  diluted 
with  water  to  4CX)  cc.     To  the  10  cc.  of  this  placed  in  a  haematinometer,  38 


Fig,  39.— Zeiss'.s  Microspcctroscope  after  Al  be. 


Fig.  40  —Adjustable  Slit  in  Fig.  39,  A. 


cc.  of  water  had  to  be  added  to  obtain  the  same  tint  as  that  of  the  standard 
solution,  so  that  the  volume  of  water  which  would  require  to  be  added  to 
dilute  the  whole  400  cc.  would  !»e  1520  cc,  thus— 

10  :  400  :  :  38  :  a; 
X  =  1520  cc. 

By  adding  1520  cc.  of  distilled  water  to  the  400  cc.  of  blood  solution,  we  get 
1920  cc.  of  the  same  tint  or  degree  of  dilution  as  the  standard  solution. 

The  standard  solution  on  analysis  was  found  to  contain  0.145  gi'ams  of 
hemoglobin  in  100  cc,  so  that  the  total  amount  of  haemoglobin  in  the  diluted 
Mood  is  found,  thus — 

100  :   1920  :  :  o.  145  :  x 
X  =  2.784  grams. 


VIII.]  SALIVARY   DIGESTION.  6^ 

Since,  however,  this  amount  of  hsemoglobin  was  obtained  from  20.186  grams 
of  the  original  blood,  the  amount  in  100  parts  will  be  found  as  follows  : — 

20.186  :  100  :  :  2.784  :  as 
^  =  13-79  grams  per  cent, 

12.  Microspectroscopes. — When  very  small  quantities  of  fluid  are  to  be 
examined,  they  are  placed  in  small  vessels  made  by  fixing  short  lengths  ol 
barometer  tubing  to  a  glass  slide.  Use  either  the  instrument  of  Browning  or 
that  t)f  Zeiss  (figs.  39,  40). 

The  instrument  is  in  reality  an  eyepiece  with  a  slit  mechanism  adjustable 
between  the  field-glass  and  eyeglass  of  an  ocular.  The  instrument  is  fitted 
into  the  tube  of  a  microscope  in  place  of  the  eyepiece.  It  consists  of  a  drum 
(A)  with  a  slit  adjustable  by  means  of  the  screws  H  and  F  (fig.  40).  Within 
the  drum  there  is  also  a  prism  whereby  light  admitted  at  the  side  of  the  drum 
is  totally  reflected  towards  the  eye  of  the  observer.  Above  the  eye-glass  is 
placed  an  Amici  prism  of  great  dispersion,  which  turns  aside  on  the  pivot  (K) 
to  allow  of  the  adjustment  of  the  object.  It  is  retained  in  position  by  the 
catch  (L).  At  N  is  placed  the  scale  of  wave-lengths,  and  its  image  can  be 
projected  on  the  spectrum  by  the  mirror  (0).  The  scale  is  adjusted  relative 
to  the  spectrum  by  the  screw  P.  The  scale  is  set  by  the  observer  so  that 
Fraunhofer's  line  D  corresponds  to  58.9  of  the  scale. 

The  fluid  to  be  examined  is  placed  in  a  suitable  vessel  on  the  stage  of  the 
microscope,  and  light  is  transmitted  through  it. 


•       LESSON  VIII. 
SALIVARY  DIGESTION. 


1.  To  Obtain  Mixed  Saliva. — Einse  out  the  mouth  with  water 
an  hour  01  two  after  a  meal.  Inhale  the  vapour  of  ether,  glacial 
acetic  acid,  or  even  cold  air  through  the  mouth,  wliich  causes  a 
reflex  secretion  of  sahva.  In 
doing  so,  curve  the  tongue  \\  ^^ 
so  as  to  place  its  tip  behind 
the  incisor  teeth  of  the  upper 
jaw.  Or  chew  a  piece  of 
caoutchouc.  In  a  test-glass 
collect  the  saliva  with  as  few 
air-bubbles  as  possible.  If 
it  be  turbid  or  contain  much 
froth,  filter  it  through  a  small 

filter  (p.  69).  ^IQ-  41.— Microscopic  Appearances  of  Saliva. 

2.  I.  Microscopic  Examination. — With  a  liigh  power  observe 
the  presence  of  (i)  squamous  epithelium,  (2)  salivary  corpuscles, 


68  PRACTICAL   PHYSIOLOGY.  [VIII. 

(3)  perliaps  cUbris  of  food,  (4)  possibly  air-bubbles,  and  (5)  fungi — 
especially  various  forms  of  bacteria  (fig,  41). 

II.  Physical  and  Chemical  Characters  (sp.  gr.  1002  -1006). 

(a.)  Observe  its  appearance — it  is  colourless  and  either  trans- 
parent or  translucent— and  that  when  poured  from  one  vessel  to 
another  it  is  glairy,  and  more  or  less  sticky.  On  standing,  it 
separates  into  two  layers ;  the  lower  one  is  cloudy  and  turbid,  and 
contains  in  greatest  amount  the  morphological  constituents. 

{b.)  Its  reaction  is  alkaline  to  litmus  paper. 

(r.)  Add  acetic  acid  =  a  precipitate  of  mucin  not  soluble  in 
excess.     Filter. 

(V/.)  With  the  filtrate  from  (c),  test  for  traces  of  proteids 
(serum-albumin  and  globulin)  with  the  xanthoproteic  reaction  and 
Millon's  test. 

(e.)  To  a  few  drops  of  saliva  in  a  porcelain  vessel  add  a  few 
drops  of  ch'Iufp  acidulated  ferric  chloride  =  a  red  colouration  due  to 
potassic  sulpho-cyanide.  The  colour  does  not  disappear  on  heat- 
ing, or  on  the  addition  of  an  acid,  but  is  discharged  by  mercuric 
chloride.  Meconic  acid  yields  a  similar  colour,  but  it  is  not 
discharged  by  mercuric  chloride.  The  sulpho-cyanide  is  pre- 
sent only  in  parotid  sahva,  and  is  generally  present  in  mixed 
saliva, 

(/.)  Test  a  very  dilute  solution  of  potassic  sulpho-cyanide  to 
compare  with  (e.). 

((/.)  Grscheidlen's  method.  Dip  filter  paper  in  weak  acidulated 
(HCl)  ferric  chloride  solution,  and  allow  it  to  dry.  Contact  with  a 
drop  of  saliva  gives  a  reddish  stain. 

(//.)  The  salts  are  tested  for  in  the  usual  way  (see  "Urine"). 
Test  for  chlorides  (HNO3  and  AgNOg),  carbonates  (acetic  acid), 
and  sulphates  (barium  chloride  and  nitric  acid). 

{i. )  Nitrites  are  often  present  in  saUva.  Add  a  little  of  the  saliva  to  starch 
paste,  containing  a  little  sulphuric  acid  and  iodide  of  potassium,  when,  if 
nitrites  be  present,  an  intense  blue  colour  is  produced. 

(./. )  To  diluted  saliva  add  a  few  drops  of  sulphuric  acid,  and  then  meta- 
diamido-benzol.  Yellow  colour  indicates  the  presence  of  nitrites.  This  re- 
action does  not  succeed  in  all  cases. 

3.  Digestive  Action. 

Starch  Solution. — Place  i  gram  of  pure  potato  starch  in  a 
mortar,  add  a  few  cc.  of  cold  water,  and  mix  well  with  the  starch. 
Add  200  cc.  of  boiling  water,  stirring  all  the  while.  Boil  the 
fluid  in  a  flask  for  a  few  minutes.  This  gives  .5  per  cent, 
solution. 

Action  of  Saliva  on  Starch  (Ptyalin,  a  diastatic  enzyme). 

(a.)  Dilute  the  sahva  with  Ave  volumes  of  water,  and  filter  it 


VIII.]  SALIVARY   DIGESTION.  69 

This  is  best  done  through  a  filter  perforated  at  its  apex  by  a  pin- 
hole. In  this  way  all  air-bubbles  are  got  rid  of.  Label  three 
test-tubes  A,  B,  and  C.  In  A  place  starch  mucilage,  in  B  saliva, 
and  in  C  I  volume  of  saliva  and  3  volumes  of  starch  mucilage. 
Place  them  in  a  water-bath  at  40°  C.  for  ten  minutes.  Test  for  a 
reducing  sugar  in  portions  of  all  three,  by  means  of  Fehling's 
solution.  A  and  B  give  no  evidence  of  sugar,  while  C  reduces 
the  Fehling,  giving  a  yellow  or  red  deposit  of  cuprous  oxide. 
Therefore,  starch  is  converted  into  a  reducing  sugar  by  the  saliva. 
This  is  done  by  the  ferment  ptyalin  contained  in  it. 

{b.)  Test  a  portion  of  C  with  solution  of  iodine  ;  no  blue  colour 
is  obtained,  as  all  the  starch  has  disappeared,  being  converted 
into  a  reducing  sugar  or  maltose. 

(r.)  Make  a  thick  starch  mucilage,  place  some  in  test-tubes 
labelled  A  and  B.  Keep  A  for  comparison,  and  to  B  add  saliva, 
and  expose  both  to  40°  C.  A  is  unaffected,  while  B  soon  becomes 
fluid — within  two  minutes — and  loses  its  opalescence  ;  this  liquefac- 
tion is  a  process  quite  antecedent  to  the  saccharifying  process 
which  follows. 

4.  Stages  between  Starch  and  Maltose. — Mix  starch  and  saliva 
as  in  3  (a.)  C,  and  place  in  a  water-bath  at  40°  C.  At  intervals  of  a 
minute  test  small  portions  with  iodine.  Do  this  by  taking  out  a 
drop  of  the  liquid  by  means  of  a  glass  rod.  Place  the  drop  on  a 
white  porcelain  plate,  and  with  another  glass  rod  add  a  drop  of 
iodine  solution. 

Note  the  following  stages : — At  first  there  is  pure  blue  with 
iodine  due  to  the  soluble  starch  formed  giving  also  a  blue  with 
iodine,  later  a  deep  violet,  showing  the  presence  of  erythro-dextrin, 
the  violet  resulting  from  a  mixture  of  the  red  produced  by  the 
dextrin  and  the  blue  of  the  starch.  Then  the  blue  reaction  entirely 
disappears,  and  a  reddish-brown  colour,  due  to  erythro-dextrin 
alone,  is  obtained.  After  this  the  reaction  becomes  yellowish- 
brown,  and  finally  there  is  no  reaction  with  iodine  at  all,  achroo- 
dextrin  being  formed,  along  with  a  reducing  sugar  or  maltose. 
The  latter  goes  on  forming  after  iodine  has  ceased  to  react  with  the 
fluid,  and  its  presence  is  easily  ascertained  by  Fehling's  solution. 
The  soluble  starch  is  precipitated  by  alcohol,  while  maltose  is 
not.     In  this  way  this  body  may  be  separated. 

5.  Effect  of  Different  Conditions  on  Salivary  Digestion. 

{a. )  Label  three  test-tubes  A,  B,  aVid  C.  Into  A  place  some  saliva,  boil  it, 
and  add  some  starch  mucilage.  In  B  and  C  place  starch  mucilage  and  saliva, 
to  B  add  a  few  drops  of  hydrochloric  acid,  and  to  C  caustic  potash.  Place 
all  three  in  a  water-bath  at  40"  C. ,  and  after  a  time  test  them  for  sugar  by 
Fehling's  solution.     No  sugar  is  formed — in  A  because  the  ferment  was  de- 


70  PRACTICAL  PHYSIOLOGY.  [VIIL 

stroyed  by  boiling,  and  in  B  and  C  because  strong  acids  and  alkalies  arrest 
the  action  of  ptyalin  on  starch. 

(h.)  If  a  test-tube  containing  starch  mucilage  and  saliva  be  prepared  as  in 
3  ((/.)  C,  and  placed  in  a  freezing  mixture,  the  conversion  of  starch  into  a  re- 
ducing sugar  is  arrested  ;  but  the  feraient  is  not  destroyed,  for  on  j)lacing  the 
test-tube  in  a  water-bath  at  40°  C,  the  conversion  is  rapidly  effected. 

(f.)  Mix  raw  starch  with  saliva  and  keep  it  at  40°  C.  Test  it  after  half  an 
hour,  when  little  or  no  sugar  will  be  found. 

6.  Starch  is  a  CJolloid,  but  Sugar  is  a  Crystalloid  and  dialyses. 

(a.)  Place  in  a  sausage  parchment  tube  (p.  78),  20  cc.  of  starch  mucilage  (A), 
and  into  another,  some  starch  mucilage  with  saliva  (B).  Suspend  A  and  B 
in  distilled  water  in  separate  vessels. 

(b.)  After  some  hours  test  the  ditfusate  in  the  distilled  water.  No  starch 
will  be  found  in  the  diffusate  of  either  A  or  B,  but  sugar  will  be  found  in  that 
of  B.  proving  that  sugar  dialyses,  while  starch  does  not.  Hence  the  necessity 
of  starch  being  converted  into  a  readily  dififusible  body  during  digestion. 

7.  Action  of  Malt-Extract  on  Starch. 

(a.)  Rub  up  10  grains  of  starch  with  30  cc.  of  distilled  water  in  a  mortar, 
add  2CXD  cc.  of  boiling  water,  and  make  a  strong  starch  mucilage. 

(b.)  Powder  5  grams  ot  pale  low-dried  malt,  and  extract  it  at  50°  C.  for  half 
an  hour  with  30  cc.  of  distilled  water,  and  filter.     Keep  the  filtrate. 

(t\)  Place  the  starch  paste  of  (a.)  in  a  flask,  and  cool  to  60°  C,  add  the  ex- 
tract of  (^>. ),  and  place  the  Ha.sk  in  a  water-bath  at  60°  C. 

(</. )  Observe  that  the  paste  soon  becomes  fluid,  owing  to  the  fonnation  of 
soluble  starch,  and  if  it  be  tested  from  time  to  time  (as  directed  in  4),  it  gives 
successively  the  tests  for  starch  and  erythro-dextrin.  Continue  to  digest  it 
until  no  colour  is  obtained  with  iodine — i.e.,  until  all  starch  and  erythro- 
dextrin  have  disappeared. 

{e.)  Take  a  portion  oi {d.)  and  precipitate  it  with  alcohol  =  achroc- dextrin. 
The  liquid  also  contains  maltose  (/".). 

{/.)  Boil  the  remainder  of  the  fluid,  cool,  filter,  and  evaporate  the  filtrate  to 
20  cc.  Add  6  volumes  of  90  per  cent,  spirit  to  precipitate  the  dextrin  :  boil, 
filter,  and  concentrate  to  dryness  on  a  water-bath,  and  dissolve  the  residue  in 
distilled  water.  The  solution  is  maltose  (C12H.j2O11-rH.2O)  If  the  alcoholic 
solution  be  exposed  to  air,  crystals  of  maltose  are  formed! 


ADDITIONAL  EXERCISES. 

8.  Compare  the  Reducing  Power  of  Maltose  and  Dextrose. 

{a.)  With  Fehling's  solution  estimate  the  reducing  power  of  the  solution 
obtained  in  7  (/. ).     (See  "  Urine. ") 

{h.)  Boil  in  a  tiask  for  half  an  hour  50  cc.  of  the  solution  of  maltose  with 
5  cc.  of  hydrochloric  acid.  Neutralise  with  caustic  soda,  and  make  up  the 
volume,  which  has  been  reduced  by  the  boiling,  to  50  cc,  and  determine  by 
Fehling's  solution  the  reducing  power.  The  acid  has  converted  the  maltose 
into  dextrose,  and  the  ratio  of  the  fonuer  estimation  (a.)  to  the  present  one 
should  be  65  to  100. 

(c.)  A  solution  of  pure  dextrose  treated  as  in  {b.)  is  not  afl"ected  in  its  re- 
ducing power. 

Saliva  has  practically  the  same  effect  on  starch  as  malt- extract,  and  may  be 
used  instead  of  the  latter. 


[X.]  GASTRIC   DIGESTION.  7 1 

9.  Tetra-Paper,  and  Oxidising  Power  of  Fluids,  e.g.,  Saliva.— The  papers 
known  as  tetva-])apcr  are  nsed  to  estimate  the  oxidising  power  of  a  fluid,  such 
as  saliva.  They  are  impregnated  Avith  tetra-mothyl-iiaraphenylene-diamine. 
Tliis  body,  with  i  atom  of  oxygen  assumes  a  violet  tint,  and  a  larger  number 
of  atoms  of  oxygen  enfeebles  or  discharges  the  colour  so  j>roduccd,  C-  Wurster 
has  made  this  the  basis  for  tlie  measurement  of  the  oxidising  power  of  lluids, 
the  ozone  of  the  air,  or  nitrous  acid.  Seven  times  as  much  oxygen  is  required 
to  destroy  the  colour  formed  as  is  necessary  to  form  it  from  the  original  tetra- 
base.  The  shades  of  colour  in  the  emj)irical  scale,  which  is  supplied  with  the 
tetra-papers,  are  obtained  by  means  of  a  s-olution  of  iodine.  A  certain  depth 
of  tint  on  the  scale  corresponds  to  a  certain  amount  of  active  oxygen  (ozone) 
])er  litre  of  the  fluid.  Tlie  papers  and  scale  are  supplied  by  Dr.  Theodor 
Schuchardt,  G()rlitz. 

(a.)  Fold  the  paper  and  place  it  on  a  white  porcelain  background.  If  the 
fluid  to  be  tested  is  alkaline,  moisten  the  paper  previously  with  a  drop  of  pure 
glacial  acetic  acid,  and  allow  a  few  drops  of  the  fluid,  e.</.,  saliva,  to  run  on 
tlie  paper.  Compare  the  colour  of  the  ])aper  with  the  Roman  numbers  on  the 
scale  ;  this  indicates  the  amount  of  ozone  per  litre.  If  the  process  be  done  in 
a  test-tube,  the  tetra-substance  is  dissolved  out  and  the  fluid  becomes  bluish. 


LESSON  IX. 
GASTRIC  DIGESTION. 


1.  Preparation  of  Artificial  Gastric  Jiiice. 

(a.)  Take  part  of  the  cardiac  end  of  the  pig's  stomach,  which  ha?5 
been  previously  opened  and  washed  rapidly  in  cold  water,  and 
spread  it,  mucous  surface  upwards,  on  the  convex  surface  of  an 
inverted  capsule.  Scrape  the  mucous  surface  firmly  with  the 
handle  of  a  scalpel,  and  rub  up  the  scrapings  in  a  mortar  with  fine 
sand.  Add  water,  and  rub  up  the  whole  vigorously  for  some  time, 
and  filter.     The  filtrate  is  an  artificial  gastric  juice. 

(h.)  V.  Wittich's  Method. — From  the  cardiac  end  of  a  pig's 
stomach  detach  the  mucous  membrane  in  shreds,  dry  them  between 
folds  of  blotting-paper,  place  them  in  a  bottle,  and  cover  them  with 
strong  glycerine  for  several  days.  The  glycerine  dissolves  the 
pepsin,  and  on  filtering,  a  glycerine  extract  with  high  digestive 
properties  is  obtained. 

(c.)  Kiihne's  Method. — Take  130  grams  of  the  cardiac  mucous  membrane 
of  a  j)ig's  stomach,  and  place  it  in  5  litres  of  water  containing  80  cc.  of  25  per 
cent,  hydrochloric  acid  {i.e.,  .2  per  cent.).  Heat  the  whole  for  twelve  hours  at 
40°  C.  Almost  all  the  mucous  membrane  is  dissolved.  Strain  through  flannel 
and  then  filter.  Tliis  is  a  ])owerfully  peptic  fluid,  but  it  contains  a  small 
quantity  of  i)eptones.  It  can  be  kept  for  a  long  time.  The  test  of  an  active 
])rei)aration  of  gastric  juice  is  that  a  thread  of  fibrin,  when  placed  in  the  fluid 
and  warmed,  should  be  dissolved  in  a  few  minutes. 


72 


PRACTICAL  PHYSIOLOGY. 


[IX. 


((f.)  Instead  of  (^7.)  or  (h,)  use  Benger's  liquor  pepticus,  or  the 
pepsin  of  Burroughs,  Wellcome,  &  Co.,  or  that  of  Park,  Davies, 
&  Co. 

All  the  above  artificial  juices,  when  added  to  hydjochloric  acid 
of  the  proper  strength,  have  high  digestive  powers. 

2.  Pepsin  and  Acid  (HCl)  are  necessary  for  Gastric  Diges- 
tion. 

(a.)  Take  three  beakers  or  large  test-tubes,  label  them  A,  B,  C. 
Put  into  A  water  and  a  few  drops  of  glycerin  extract  of  pepsin  or 
powdered  pepsin.  Fill  B  two-thirds  full  of  hydrochloric  acid  0.2 
per  cent.,  and  till  C  two-tliirds  full  with  0.2  per  cent,  of  hydrocliloric 
acid,  and  a  few  drops  of  glycerin  extract  of  pepsin.  Put  into  all 
tliree  a  small  quantity  of  well-washed  fibrin,  and  place  them  all  in 
a  water-bath  at  40°  C.  for  half  an  liour. 

(h.)  Examine  them.  In  A,  the  fibrin  is  unchanged ;  in  B,  the 
fibrin  is  clear  and  swoUen  up ;  in  C,  it  has  disappeared,  having 
first  become  swollen  up  and  clear,  and  completely  dissolved,  being 
finally  converted  into  peptones.  Therefore,  both  acid  and  ferment 
are  required  for  gastric  digestion. 

The  results  obtained,  all  the  tubes  being  at  40°  C,  are  : — 


Tl'be  a. 

Tube  B. 

Tube  C. 

Water. 
Pepsin. 
Fibrin. 

Water. 

Hydrochloric  acid. 
Fibrin. 

Water. 
Pepsin. 

Hydrochloric  acid. 
Fibrin. 

After  Twenty  Minut 

ES. 

Unchanged. 


Fibrin  begins  to  swell  up 
becomes  clear,  and 
small  quantity  of  acid 
albumin  formed. 


Acid  albumin  formed 
(precipitated  on  neu 
tralisation).  albumoses 
formed  (precipitated  by 
(NH4),>S0,).  and  small 
quantity  of  peptones. 


Afteb  One  Hour. 


Unchanged. 


More  acid-albumin 
formed. 


Small  amount  (or  no) 
acid  -  albumin  ;  albu- 
moses, and  much 
peptone. 


IX.] 


GASTRIC   DIGESTION. 


73 


FlQ.  42.— Digestion-Bath. 


3.  Hydrochloric  Acid  of  0-2  per  cent.— Add   6.5  cc   oi  ordinary  com- 
mercial hydrochloric  acid  to  i  litre  of  distilled  water. 

4.  Products  of  Peptic  Digestion  and  its  Conditions. 

(a.)  Half  fill  three  large  test-tubes,  labelled  A,  B,  C,  with 
hydrocliloric  acid  0.2  per  cent.  Add  to  each  five  drops  of  glycerin 
extract  of  pepsin.  Boil  B,  and 
make  C  faintly  alkaline  with 
sodic  carbonate.  The  alkalinity 
may  be  noted  by  adding  pre- 
viously some  neutral  litmus 
solution.  Add  to  each  an  equal 
amount — a  few  threads  of  well- 
washed  fibrin — which  has  been 
previously  steeped  for  some  time 
in  0.2  per  cent,  hydrochloric 
acid,  so  that  it  is  swollen  up 
and  transparent.  Keep  the 
tubes  in  a  water-bath  (fig.  42) 
at  40°  C.  for  an  hour,  and  ex- 
amine them  at  intervals  of 
twenty  minutes. 

(b,)  After  five  to  ten  minutes, 
or  less,  the  fibrin  in  A  is  dissolved,  and  the  fluid  begins  to  be 
turbid.  In  B  and  C  there  is  no  change.  Even  after  long  exposure 
to  40°  C.  there  is  no  change  in  B  and  C.  After  three-quarters  of 
an  hour  filter  A  and  part  of  B  and  C.     Keep  the  filtrates. 

(c.)  Carefully  neutrahse  the  filtrate  of  A  with  dilute  caustic 
soda  =  a  precipitate  of  acid-albiunin.  Filter  off  this  precipitate, 
dissolve  it  in  0.2  per  cent,  hydrochloric  acid.  It  gives  proteid 
reactions  (Lesson  I.  7). 

{<L)  Test  the  filtrate  of  (c.)  for  alhumose  or  proteose.  Repeat 
all  the  tests  for  albumose  (Lesson  I.  10).  Albumose  is  soluble  in 
water,  and  gives  all  the  ordinary  proteid  reactions.  It  is  precipi- 
tated by  nitric  acid  in  the  cold  in  presence  of  NaCl,  but  the 
precipitate  is  redissolved  with  the  aid  of  heat,  and  reappears  on 
cooling.  This  is  a  characteristic  reaction.  It  is  precipitated  by 
acetic  acid  and  ferrocyanide  of  potassium ;  by  acetic  acid  and  a 
saturated  solution  of  sodic  sulphate  ;  and  by  metaphosphoric  acid  : 
while  peptones  are  not.  It  gives  the  biuret  reaction  (like  peptone). 
Like  peptones,  it  is  soluble  in  water. 

(e.)  To  part  of  the  filtrate  of  {c.)  add  neutral  ammonium  sul- 
phate to  saturation.  This  precipitates  all  the  albumoses,  while 
the  peptones  are  not  precipitated,  but  remain  in  solution.  Filter 
and  test  the  filtrate  for  peptones  (Lesson  I.  10).     In  the  biuret 


74  PRACTICAL  PHYSIOLOGY.  [iX. 

reaction  owing  to  the  presence  of  (NH4)2S04  a  great  excess  of  soda 
has  to  be  added. 

(/'.)  Keutralise  part  of  the  filtrates  of  B  and  C.  They  give  no 
precipitate,  nor  do  they  give  the  reactions  for  peptones.  In  B  the 
ferment  pepsin  was  destroyed  by  boiling,  while  in  C  the  ferment 
cannot  act  in  an  alkaline  medium. 

{g.)  If  to  the  remainder  of  C  acid  be  added,  and  it  be  placed 
again  at  40°  C,  digestion  takes  place,  so  that  neutralisation  has  not 
destroyed  the  activity  of  the  ferment. 

Instead  of  fibrin  white  of  egg  may  be  used. 

The  methods  used  by  Kiihne  to  isolate  the  varieties  of  albumose 
are  purposely  omitted  here  (p.  78). 


Products  of  Gastric  Digestion. 

To  50  grams  well-washed  and  boiled  fibrin  +  250  cc  0.2  per  cent. 
HCl.  Digest  for  twenty-four  hours  at  40°  C.  Neutralise  with  sodium 
carbonate. 


Precipitate =Acid-  Filtrate  :  Albumose  +  Peptone, 

albumin.  '  Saturate  with  (NH4)2S04. 


Precipitate  =  A  Ibumoses.  Filtrate  :  Peptone  +  (N"H4)2S04. 

Boil  with  Barium  Carbonate.  Boil  with  Barium  Carbonate. 


I 

Residue  of        Filtra,te^  A lbu7nose-  Residue  of         Filtrate  =  Pe//<(m<j- 

Barium  Sulphate,    solution  wliich  can  Barium  Sulphate,  solution  containing 

be  precipitated  by  Baryta.  Precipitate 

alcohol.  peptone  by  alcohol. 

5.  Tests  for  Albumose  (Lesson  I.  10). — It  is  precipitated  by 
the  following  substances  :  Nitric  acid ;  acetic  acid  and  NaCl ;  acetic 
acid  and  ferrocyanide  of  potassium.  The  precipitates  are  soluble 
on  heating  and  reappear  on  cooling.  In  all  these  respects  it 
diff'ers  from  peptone.  Like  peptone,  however,  it  gives  the  biuret 
reaction,  and  is  not  coagulated  by  heat. 

6.  Test  for  Peptones  (Lesson  I.  10,  VI.). 

The  following  table  from  Halliburton  shows  at  a  glance  the  chief 


IX.] 


GASTRIC    DIGESTION. 


75 


characters   of   the    final    product    peptone,   and   the    intermediate 
albumoses  in  contrast  with  those  of  a  native  proteid  like  albumin. 


Variety  of 
Proteid. 

Action  of 
Heat. 

Action  of 
Alcohol. 

Action  of 
Nitric  acid. 

Action  of 

(NH4)oS04. 

Action  of 
NaHO  +  CuSO*. 

Diffusi- 
biUty. 

Albumin. 

Proteoses 
Albumoses). 

Peptones. 

Coagu- 
lated. 

Not  coagu- 

Not  coagu- 
lated. 

•J^  Then  coagu- 
"•^.lated. 

•I-  But  not 
'     coagulated. 

■^^  But  not 
'     coagulated. 

•I'  In  cold,  not 

*     readily 
soluble  on 
heating. 

J^  In  cold, 
'     soluble  on 
heating,  re- 
appearing 
on  cooling. 

Not  pre- 
cipitated. 

Precipitated. 
Precipitated. 

Not  precipi- 
tated. 

Violet  colour. 

Rose-red 
colour 
(biuret  re* 
action). 

Rose-red 
colour 
(biuret  re- 
action). 

Nil. 
Slight. 

Great. 

(The  •!•  indicates  precipitated.) 

7.  Action  of  Gastric  Juice  on  Milk. 

(a.)  Mix  5  cc.  of  fresh  milk  in  a  test-tube  with  a  few  drops  of 
neutral  artificial  gastric  juice ;  keep  at  40°  C.  In  a  short  time  the 
milk  curdles,  so  that  the  tube  can  be  inverted  without  the  curd 
falling  out.  By-and-by  whey  is  squeezed  out  of  the  clot.  The 
curdling  of  milk  by  the  rennet  ferment  present  in  the  gastric  juice 
is  quite  difi'erent  from  that  produced  by  the  "souring  of  milk," 
or  by  the  precipitation  of  caseinogen  by  acids.  Here  the  casein 
(carrying  with  it  most  of  the  fats)  is  precipitated  in  a  neutral  fluid. 

(5.)  To  the  test-tube  add  5  cc.  of  0.4  per  cent,  hydrochloric  acid, 
and  keep  at  40°  C.  for  two  hours.  The  pepsin  in  the  presence  of 
the  acid  digests  the  casein,  gradually  dissolving  it,  forming  a  straw- 
yellow-coloured  fluid  containing  peptones.  The  "  peptonised  milk  " 
has  a  peculiar  odour  and  bitter  taste. 

(c.)  Peptonised  Milk. — To  5  cc.  of  milk  in  a  test-tube  add  a 
few  drops  of  Benger's  liquor  pepticus,  and  place  in  a  water-bath. 
Observe  how  the  caseinogen  first  clots,  and  is  then  partially  dissolved 
to  form  a  yellowish-coloured  fluid,  with  a  bitter  taste  and  peculiar 
odour.  There  generally  remains  a  very  considerable  clot  of  casein ; 
and,  in  fact,  the  gastric  digestion  of  milk  is  slow,  especially  if  com- 
pared with  its  tryptic  digestion  (Lesson  X.  11).  Test  the  fluid  for 
peptones  with  the  biuret  reaction,  and  observe  the  light-pink  colour 
obtained.  The  bitter  taste  renders  milk  "  peptonised "  by  gastric 
juice  unsuitable  for  feeding  purposes. 

8.  Action  of  Rennet  on  Milk. — (Rennin  the  enzyme.) 

(a.)  Place  milk  in  a  test-tube,  add  a  drop  or  two  of  rennet,  and 


'j6  PRACTICAL   PHYSIOLOGY.  [iX. 

place  the  tube  in  a  water-bath  at  40°  C.  Clark's  commercial  rennet 
will  do.  Rennet  is  obtained  from  the  fourth  stomach  of  the  calf. 
The  milk  becomes  solid  in  a  few  minutes,  forming  a  curd,  and 
by-and-by  the  curd  of  casein  contracts  and  squeezes  out  a  fluid — 
the  whey. 

{h.)  Repeat  the  experiment,  but  previously  boil  the  rennet.  No 
such  result  is  obtained  as  in  (a.),  because  the  rennet  ferment  or 
rennin  is  destroyed  by  heat. 

9.  Comparison  of  Mineral  and  Organic  Acids. 

(a.)  Take  two  test-tubes  A  and  B.  Place  in  A  10  cc.  of  a  0.2 
per  cent,  solution  of  hydrochloric  acid,  and  in  B  10  cc.  of  a  2  per 
cent,  solution  of  acetic  acid.  To  both  add  a  few  drops  of 
oo-Tropaeolin  dissolved  in  alcohol  The  very  dilute  mineral  acid 
in  A  renders  it  rose-pink,  while  the  organic  acid  does  not  affect  its 
colour.  Or,  what  is  perhaps  a  better  method,  allow  a  drop  of  a 
saturated  alcohoHc  solution  to  evaporate  on  a  white  porcelain  slab  at 
40°  C,  and  while  at  this  temperature  add  a  drop  of  the  acid  solution. 
On  evaporation  a  violet  tint  indicates  an  inorganic  acid,  .005  HCl 
can  be  thus  detected  {Langley).  It  is  stated  not  to  be  quite  a 
rehable  test  in  the  presence  of  certain  organic  matters. 

{h.)  Repeat  (a.),  but  add  to  the  acids  a  dilute  watery  solution  of 
methyl-violet,  and  note  the  change  of  colour  produced  by  the 
mineral  acid.  It  becomes  blue  and  then  green.  If  a  strong  solution  of 
acid  be  used,  the  colour  is  discharged,  but  this  is  never  the  case 
with  the  percentage  of  acid  in  the  stomach.  The  peptones  in 
gastric  juice  may  be  precipitated  by  the  previous  addition  of  10  per 
cent,  tannic  acid,  and  tlien  the  test  can  be  applied.  In  the  presence 
of  proteids  in  gastric  juice  it  does  not  give  absolutely  reliable  results. 

(c.)  Repeat  (a.)  with  the  same  acids,  but  use  paper  stained  with 
congo-red,  and  observe  the  change  of  colour  to  blackish-blue  or 
intense  blue  produced  by  the  hydrochloric  acid.  "Wash  in  ether ; 
if  the  red  colour  reappears  the  acid  is  organic,  if  not,  mineral. 
Organic  acids  make  it  violet,  not  blue. 

{d.)  Phloro-Ghicin  and  Vanillin  {Gunzburg). — Dissolve  2  grams  of  phloro- 
glucin  and  i  gram  of  vanillin  in  roc  cc.  alcohol.  Mix  equal  quantities  of  this 
with  the  fluid  to  be  tested,  and  evaporate  the  mixture  in  a  watch-glass  on  a 
water-bath.  Do  not  allow  the  fluid  to  boil.  The  presence  of  HCl  is  shown 
by  the  formation  of  a  delicate  rose-red  tinge  or  stain,  or,  if  there  be  much 
hydrochloric  acid,  of  red  crystals.  This  reaction  will  detect  .06  per  cent. 
HCl,  and  is  said  not  to  be  impeded  by  organic  acids,  albumin,  or  peptone. 
The  test  is  an  expensive  one. 

{e. )  Benzo-Purpurin  6  B.  —Use  blotting-papers  soaked  in  a  saturated  watery 
solution  of  this  fluid  and  dried.  HCl  (.4  grm.  in  100  cc.)  makes  them  dark 
blue,  while  organic  acids  make  them  brownish-violet.  If  both  HCl  and 
organic  acids  be  present,  the  stain  is  brownish-black  ;  but  if  the  stain  be 
suspected  to  be  partly  due  to  HCl,  wash  the  paper  in  a  test-tube  with 
sulphxiric  ether,  which  removes  the  stain  due  to  the  organic  acid,  leaving  that 


[X.]  GASTRIC  DIGESTION.  JJ 

due  to  the  HCl  unafFected.  The  sulphuric  ether  does  not  affect  the  mineral 
acid  stain. 

(/.)  Mohr's  Test. — Mix  together  2  cc.  of  a  10  per  cent,  solution  of  sulpho- 
cyanide  of  potassium,  0.5  cc.  of  a  neutral  solution  of  ferric  acetate,  and  8.5  cc. 
water.  Place  a  few  drops  of  this  ruby-red  fluid  on  a  porcelain  capsule,  and 
allow  a  few  drojjs  of  the  gastric  juice  to  mix  with  it  =  a  light  violet  colour  at 
the  point  of  contact,  and  a  mahogany  brown  when  the  fluids  mix.  It  is  less 
sensitive  than  the  aniline  tests. 

{g.)  Shake  up  a  mixture  of  dilute  HCl  and  an  organic  acid,  e.g.,  lactic,  with 
ether.  Remove  the  ether,  and  on  evaporating  it,  it  will  be  found  to  have 
dissolved  the  organic  acid,  but  not  the  mineral  one.  On  this  fact  is  based 
Eichet's  method  of  determining  the  amount  of  an  organic  acid  in  presence  of 
a  mineral  acid. 

These  reactions  for  a  mineral  acid  are  specially  to  be  noted,  as 
they  are  used  clinically  for  ascertaining  the  presence  or  absence  of 
hydrochloric  acid,  e.^.,  in  a  vomit.  This  acid  is  frequently  absent 
from  the  gastric  juice  in  cancer  of  the  stomach.  In  gastric  catarrh 
the  HCl  may  be  greatly  diminished  and  lactic  acid  abundant.  The 
presence  of  peptones  interferes  with  the  delicacy  of  some  of  these  re- 
actions.   The  reactions  (c),  ((^.),  (e.),  are  the  most  to  be  depended  on. 

10.  Carbolo-Chloride  of  Iron  Test  for  Lactic  Acid  {Uffelmann). — Prepare 
a  fresh  solution  by  mixing  10  cc.  of  a  4  per  cent,  solution  of  carbolic  acid  with 
20  cc.  of  distilled  water,  and  i  drop  of  liquor  ferri  perchloridi.  The 
amethyst-blue  solution  thus  obtained  is  changed  to  ydlow  by  lactic  acid,  while 
it  is  not  affected  by  0.2  per  cent.  HCl;  but  alcohol,  sugar,  and  phosphate, 
yield  a  similar  reaction. 

A  faintly  yellow- coloured  solution  of  ferric  chloride  (2-5  drops  to  50  cc.  water) 
is  not  affected  by  the  addition  of  HCl,  acetic,  or  butyric  acid,  but  it  is  inten- 
sified in  the  presence  of  dilute  lactic  acid. 


ADDITIONAL  EXEECISES. 

[Proteids,  e.g.,  albumin,  are  split  up  by  certain  acids  and  ferments,  as 
shown  by  Kuhne,  into  an  anti -group  and  a  hemi -group.  In  the  case  of 
ferments,  the  following  scheme  represents  the  results  : — 

Action  of  Enzymes  {Ferments), 
Albumin. 


•1:2 

OT3 


|S 


Ampho-peptone. 


Hemi-peptone.  Hemi-peptone. 


Leucin,    Tyrosin,  Leucin,    Tyrosin, 
V    &c.  &c. 


^  3 


78 


PRACTICAL  PHTSIOLOGT. 


[IX. 


•  The  anti-group  is  not  further  split  up,  but  the  hemi-group,  aUhough  not 
split  up  by  peptic  digestion,  is  split  up  by  tryptic  digestion  into  leucin, 
tyrosin,  and  other  yiroducts. 

The  substance  hitherto  called  hemi-albumose  has  been  shown  by  Kiihnp 
to  consist  of  three  alhunioses,  viz.,  proto-albumose,  hetero-albiimose,  and 
deutero-albumose.  The  first  two  are  precipitated  by  NaCl,  and  the  last  by 
NaCl  and  acetic  acid.  For  separation  of  these  bodies — which  can  be  obtained 
most  easily  from  Witte's  peptone — see  13, 


capsule,  cover  it  with 


11.  To  Prepare  Albumose  and  (Jastric  Peptones  in  Quantity. 

{ft.)  Place  lo  grams  of  fresh,  well-washed,  expressed  fibrin  in  a  porcelain 
300  cc.  of  0.2  per  cent,  hydrochloric  acid,  and  keep  the 
whole  at  40°  C.  in  a  water-bath  until  the  whole  of 
the  fibrin  is  so  swollen  up  as  to  become  converted 
into  a  perfectly  clear,  jelly-like  mass,  and  it  becomes 
so  thick  that  a  glass  rod  is  supported  erect  in  it, 

(6.)  Add  I  or  2  cc.  of  glycerin  pepsin  extract  or 
the  artificial  gastric  juice,  i  (c),  and  stir  the  mass. 
Within  a  few  minutes  the  whole  becomes  fluid. 

(c.)  After  a  short  time— fifteen  to  twenty  minutes 
— Isefore  the  peptonisation  is  complete,  filter  and 
exactly  neutralise  the  filtrate  with  ammonia  or 
caustic  soda,  which  precipitates  the  acid  albumin 
with  a  small  quantity  of  the  albumoses.  Filter  ; 
the  filtrate  contains  the  albumoses,  which  can  be 
precipitated  by  saturation  with  crystals  of  neutral 
ammonium  sulphate.  To  get  rid  of  this  salt  the 
precipitate  must  be  dialysed  in  a  Kiihne's  dialyser 
(fig.  43).] 

12.  Comparative  Digestive  Power  of  Pepsins, 
e.g.,  the  various  pepsins  found  in  the  market,  or 
the  comparative  digestive  power  of  glycerine  ex- 
tracts of  the  stomach.  Chop  up  well-washed  and 
boiled  fibrin,  and  stain  it  with  ammoniacal  carmine 
(24  hours).  Wash  thoroughly  and  preserve  under 
ether.     Place  in  the  requisite  number  of  beakers 

vta    .-     ini\.^^'r.  T.:oi,-=^,  .2  per  cent.  HCl.,  equal  amounts  of  the  carmine 

FlQ.  43. — Kunne  8  Dialvser.  £,  ^  j    ii  jj    j.i.  •         1  j.  .1 

A  parchment  tube,  such  as  II t»nn,   and   then  aaa   tne   pe])Sin   whose  strength 

is  used  for  sausages,  is  sus-  is  to  be  tested  ;  keep  at  40'  C.     As  the  fibrin  is 

pended  in  a  vessel  through  digested  the  carmine  is  set  free,  so  that  the  most 

SiallyVow'ing.^^''"' deeply-stained    liquid    contains    the    most    active 

pepsin  {GriUzner's  Method). 


13.  Albumoses. — Dissolve  Witte's  peptone  in  10  per  cent,  sodium  chloride 
solution  and  filter.  This  solution  does  not  coagulate  on  heating,  but  gives 
the  ordinary  proteid  reactions,  together  with  "biuret  and  nitric  acid  tests 
(Lesson  I.). 

(a.)  Saturate  the  solution  with  (NH4X;S04  =  precipitate  of  albumoses. 
Filter.     The  peptone  is  in  the  filtrate  and  can  be  precipitated  by  alcohol. 

(6.)  Dialyse  another  portion  of  the  solution;  hclero-albumose  is  precipitated. 

(c.)  Faintly  acidify  another  portion  of  the  solution,  and  then  saturate  it 
with  sodium  chloride  =  precipitate  of  proto-albumose  and  hetero-albumose. 
Filter.  The  filtrate  contains  the  deutero-albumose  and  peptone.  Precipitat« 
the  deutero-albumose  by  saturating  with  ammonium  sulphate. 


X.]  PANCREATIC  DIGESTION.  79 

14.  Chemical  Examination  of  the  Gastric  Contents,  e.g.,  Vomit. 

{a.)  Test  the  reaction. 

[h.)  Determine  the  acidity  {e.g.,  of  lo  cc.)  by  means  of  a  deci-normal  solution 
of  caustic  soda.     (See  "Urine.") 

(c.)  Test  lo  cc.  for  the  presence  of  pepsin  (digest  with  fibrin  and  HCl),  and 
rennet  (milk). 

(d.)  Use  the  tests  9  (c),  {d.\  (e.),  for  determining  the  presence  of  free 
HCl. 

{e. )  Make  a  rough  estimate  of  the  presence  of  lactic,  butyric,  and  acetic  acids 
by  the  method  9  {g.). 

(/.)  Examine  for  proteids,  e.g.,  albumin,  albumoses,  and  peptone. 

{g.)  Test  for  sugar  and  its  digestive  products. 

(h.)  Distil  some  of  the  fluid,  extract  the  remainder  with  sulphuric  ether,  and 
in  the  latter  estimate  the  lactic  acid  which  it  contains. 

(t.)  Test  Meal.— When  it  is  desired  to  know  if  digestion  is  normal  a 
test-meal  is  given.  Ewald  recommends  a  roll  of  stale  bread  taken  on  an 
empty  stomach,  with  tea  or  water.  After  an  hour  the  contents  of  the  stomach 
are  pumped  out  by  means  of  a  stomach  pump,  and  examined  as  above. 


LESSON  X. 

PANCREATIC    DIGESTION. 

1.  Preparation  of  Artificial  Pancreatic  Juice. 

{(I.)  Mince  a  portion  of  the  pancreas  of  an  ox  twenty-four  hours 
after  death,  rub  it  up  with  well-washed  line  sand  in  a  mortar,  and 
digest  it  with  cold  water,  stirring  vigorously.  After  a  time  strain 
through  muslin,  and  then  filter  through  paper.  The  filtrate  has 
digestive  properties,  chiefly  upon  starch.  Instead  of  water,  a  more 
potent  solution  is  obtained  by  digesting  the  pancreas  at  40°  C.  for 
some  hours  with  a  2  per  cent,  solution  of  sodic  carbonate.  To  pre- 
vent the  putrefactive  changes  which  are  so  apt  to  occur  in  all 
pancreatic  fluids,  add  a  little  10  per  cent,  alcoholic  solution  of 
thymol. 

{h.)  Make  a  glycerin  extract  of  the  pancreas  (pig)  in  the  same 
way  as  described  for  the  stomach  (Lesson  IX.  1,  h).  Before 
putting  it  in  glycerin,  it  may  be  placed  for  two  days  in  absolute 
alcohol  to  remove  all  the  water.  The  glycerin  extract  acts  on 
starch  and  proteids. 


8o  PRACTICAL  PHYSIOLOGY.  [X. 

(r.)  For  most  experiments  use  the  "  liquor  pancreaticus "  of 
Benger,  or  of  Savory  &  Moore,  or  Burroughs,  Wellcome  &  Co. 

{d.)  Weigh  the  pancreas  taken  from  a  pig  just  killed,  rub  it  up  with  sand  in 
a  mortar,  and  add  i  ec.  of  a  i  per  cent,  solution  of  acetic  acid  for  every  gram 
of  pancreas.  Mix  thoroughly,  and  after  a  quarter  of  an  hour  add  lo  cc.  of 
glycerin  for  every  gram  of  pancreas.  After  five  days  filter  off  the  glycerin 
extract.  The  acetic  acid  is  added  to  convert  the  unconverted  "zymogen" 
into  trypsin. 

{e.)  Kiihne's  Dry  Pancreas  Powder. — This  is  obtained  by  thoroughly 
extracting  a  pancreas  with  alcohol  and  ether,  and  drying  the  residue.  The 
extraction  must  be  done  in  an  ether  fat-extracting  apparatus;  and  as  the 
process  is  somewhat  tedious,  it  is  better  to  buy  the  substance.  It  can  be 
obtained  from  Dr.  Grlibler  of  Leipzig.  Extract  the  dry  pancreas  powder  with 
five  parts  of  a  .2  per  cent,  solution  of  salicylic  acid,  and  keep  it  at  about  40°  C. 
for  eight  or  ten  hours.  Use  20  grams  of  the  dry  pancreas  to  100  cc.  of 
salicylic  acid  fluid.  Strain  it  through  muslin,  and  press  out  all  the  fluid 
from  the  residue.  The  hands  must  be  well  washed,  as  pancreatic  digests  are 
so  liable  to  undergo  putrefaction.  It  is  well  to  cover  the  vessel  with  paper 
moistened  with  an  alcoholic  solution  of  thymol.  A  dense,  tough,  elastic 
residue  is  obtained.  Re-extract  the  latter  for  several  hours  at  90°  C.  with 
sodic  carbonate  solution  (.25  per  cent,\  adding  a  few  drops  of  alcoholic  solu- 
tion of  thymol.  1-  iljer  the  first  extract  and  allow  it  to  stand.  Very  probably 
a  large  mass  of  crystals  of  tyrosin  will  separate.  Filter  off  the  deposit  and 
mix  the  salicylic  and  alkaline  extracts.  The  extract  has  only  proteolytic  pro- 
perties. I  find  this  extract  acts  much  more  energetically  than  those  prepared 
in  other  ways.  What  remains  after  the  action  of  salicylic  acid  and  sodic  car- 
bonate contains  leucin  and  tyrosin. 

(/.)  Solution  of  Pancreatic  Enzymes. — Apart  from  the  fat-splitting  ferment 
or  enzyme,  the  other  ferments  are  readily  extracted  from  the  gland — under 
certain  conditions  by  (i.)  glycerin,  (ii.)  saturated  watery  solution  of  chloro- 
form {Roberts),  but  the  chloroform  extract  interferes  with  the  reaction  for 
grape-sugar.  Harris  and  Gow  find  that  a  saturated  solution  of  common  salt 
extracts  all  the  pancreatic  enzymes  (save  the  fat-splitting).  Roberts  found 
that  by  extracting  the  pancreas  with  a  solution  containing  a  mixture  of 
boracic  acid  and  borax  a  serviceable  extract  was  obtained. 

2.  I.  Action  on  Starch  (Amylopsin  the  ferment). 

(a.)  To  thick  starch  mucilage  in  a  test-tube  add  glycerin  extract 
of  pancreas  or  liquor  pancreaticus,  and  place  it  in  a  water  bath  at 
40°  C.  Rapidly  the  starch  paste  becomes  fluid,  loses  its  opal- 
escence, and  becomes  clear.  Within  a  few  minutes  some  of  the 
starch  is  converted  through  intermediate  stages  (p.  69)  into 
maltose.     Test  for  sugar  (Lesson  III.  8,  V.). 

(6.)  Pancreatic  Juice  and  Bile. — Repeat  A,  but  add  a  little  bile, 
the  starch  disappears  more  quickly.  Prove  by  testing  on  a  white 
porcelain  slab,  as  in  Lesson  VIII.  4. 

3.  The  same  conditions  obtain  as  for  saliva  (Lesson  "VTII.  5). 


X.]  PANCREATIC  DIGESTION.  8 1 

4.  II.  Proteolytic  Action  and  its  Conditions  (Trypsin  the  fer- 
ment). 

(a.)  Half- fill  three  test-tubes  A,  B,  C,  with  i  per  cent,  solution 
of  sodium  carbonate,  and  add  5  drops  of  glycerin  pancreatic  extract 
or  liquor  pancreaticus  in  each.  Boil  B,  and  make  C  acid  with  dilute 
hydrochloric  acid.  Place  in  each  tube  an  equal  amount  of  well- 
washed  fibrin,  plug  the  tubes  with  cotton- wool,  and  place  all  in  a 
water-bath  at  40°  C. 

(b.)  Examine  them  from  time  to  time.  At  the  end  of  one,  two, 
or  three  hours  there  is  no  change  in  B  and  C,  while  in  A  the  fibrin 
is  gradually  being  eroded,  and  finally  disappears,  but  it  does  not 
swell  up,  the  solution  at  the  same  time  becoming  slightly  turbid. 
After  three  hours,  still  no  change  is  observable  in  B  and  C. 

(c.)  Filter  A,  and  carefully  neutralise  the  filtrate  with  very 
dilute  hydrochloric  or  acetic  acid  =  a  precipitate  of  alkali-albumin. 
Filter  off  the  precipitate,  and  on  testing  the  filtrate,  peptones  are 
found.  The  intermediate  bodies,  the  albumoses,  are  not  nearly  so 
readily  obtained  from  pancreatic  as  from  gastric  digests. 

(d.)  Filter  B  and  C,  and  carefully  neutralise  the  filtrates.  They 
give  no  precipitate.     No  peptones  are  found. 

{e. )  Test  the  proteolytic  power  of  an  extract  of  Kiihne's  **  pancreas  powder  " 
(Lesson  X.,  i,  e).  For  this  purpose  the  salicylic  and  alkaline  extracts  are 
mixed  with  well-washed  fibrin  and  digested  at  40°  C.  for  ten  hours  or  longer. 
The  vessel  is  covered  with  thymolised  paper.  Strain  through  linen  and 
then  filter.  Test  the  digest  for  peptones.  It  is  diflBcult  to  get  any  albumoses 
after  this  time  ;  the  anti-albumoses  are  already  converted  into  anti-peptones, 
the  hemi-albumose  into  hemi-peptone,  and  some  of  the  latter  is  decomposed 
into  leucin  and  tyrosin. 

As  putrefaction  takes  place  with  great  rapidity  in  pancreatic 
digests,  it  is  essential  to  prevent  this  either  by  the  addition  of  an 
alcoholic  solution  of  thymol  or  chloroform  water  (5  cc.  chloroform 
to  I  litre  water).  To  get  satisfactory  results  it  is  better  to  do  it  on 
a  somewhat  larger  scale  {Salkoivski). 

Tryptic  Digestion, 

50  grams  fibrin  +  200  cc.  alkaline  (carbonate  of  soda  i  per  cent.)  chloroform 
water  +  liq.  pancreaticus  digested  for  36  hours  ;  then  boil  and  filter. 


I  I 

Residue  ;  coagulated  Filtrate  (A)  (reaction  with  bromine) 

Proteid.  concentrated      by      evaporation 

and  allowed  to  stand. 

I 

I  "■  I 

Deposition  (B)  of  Filtrate      (C)      further 

Tyrosin.  concentrated  ;  Leucin 

and  Peptone. 
F 


82  PRACTICAL   PHYSIOLOGY.  [X, 

5.  Products  other  than  Peptones. — Leucin  (CgHigNOg)  and 
Tyrosin  (C.H^.NOg). 

(a.)  Place  300  cc.  of  a  i  per  cent,  solution  of  sodic  carbonate  in 
a  flask,  add  5  grams  of  fibrin,  5  cc.  of  glycerine  extract  of  pancreas, 
and  a  few  drops  of  an  alcoholic  solution  of  thymol.  Keep  all  at 
38°  C.  on  a  water-bath  for  ten  to  sixteen  hours,  shaking  frequently. 
After  sixteen  hours  take  a  portion  of  the  mixture,  filter,  and  to  the 
filtrate  cautiously  add  dilute  acetic  acid  to  precipitate  any  alkah- 
albumin  that  may  be  present  in  it.  Filter,  and  evaporate  the 
filtrate  to  a  small  bulk,  and  precipitate  the  peptones  by  a  consider- 
able volume  of  alcohol.  Filter  to  remove  the  peptones,  and  eva- 
porate the  alcoholic  filtrate  to  a  small  bulk,  and  set  it  aside,  when 
tyrosin  and  leucin  separate  out.  Keep  them  for  microscopic  examin- 
ation (figs.  44,  79). 

(h.)  A  much  better  method  of  obtaining  leucin  and  t3n:osm  is  to 
digest,  at  40°  C,  for  twenty-four  to  thirty-six  hours,  equal  parts  of 
fresh  moist  fibrin  and  ox-pancreas  in  i  htre  of  i  per  cent,  sodium 
carbonate  solution  to  which  some  thymol  has  been  added,  or,  an 
ox-pancreas  is  digested  in  the  same  way,  the  white  of  an  egg  being 
added  every  ten  hours  (Digest  A).  Make  another  digest;  but 
do  not  add  thymol.  Digestion  and  putrefaction  take  place,  the 
latter  causing  a  most  disagreeable  smell  (Digest  B).  Filter  the 
digest  A,  and  to  some  of  it  add  ^lillon's  reagent,  which  precipitates 
any  albumin.    Filter,  boil  the  filtrate,  a  red  colour  indicates  tyrosin. 

Concentrate  some  of  the  filtered  digest  A  by  boiling  it  to  a  small 
bulk  on  a  water-bath.  After  several  hours  examine  a  drop  micro- 
scopically for  leucin  and  tyrosin.  Precipitate  the  peptones  in  some 
of  the  filtered  digest  A  by  alcohol.  Filter.  Concentrate  the  filtrate 
on  a  water-bath,  when  a  sticky  deposit  of  leucfn  is  formed. 

The  digest  A  yields  the  chlorine  or  "  bromine  reaction." 

The  digest  B  is  to  be  used  for  testing  for  the  products  of  putre- 
faction. 

(c.)  Examine  the  crystals  of  leucin  and  tyrosin  microscopically 
(figs.  44,  79).  The  former  occurs  as  brown  balls,  often  with 
radiating  lines,  not  unlike  fat,  but  much  less  refractive,  and  the 
latter  consists  of  long  white  shining  needles  arranged  in  sheaves 
or  in  a  stellate  manner,  or  somewhat  felted.     (See  "  Urine.") 

(d.)  Test  for  T3n:osin  (Hofmann). — Dissolve  some  crystals  by 
boiling  them  in  water,  add  Millon's  reagent,  and  boil,  which  gives 
a  red  colour.  The  deposit  which  is  sometimes  formed  in  Benger'a 
liquor  pancreaticus  consists  of  tyrosin. 

(g. )  Test  a  solution  of  tyrosin,  obtained  by  the  prolonged  boiling  of  horn- 
Bbavings  and  sulphuric  acid,  with  Millon's  reagent  as  in  (d.). 


X.]  PANCREATIC   DIGESTION.  83 

6.  Putrefactive  Products  of  Pancreatic  Digestion. — These  include  indol, 
skatol,  phenol,  volatile  fatty  acids,  CO.,,  H.S,  CH4,  and  H. 

/CH=CH 
Indol  CbHZ  -^ — -^    =  C^HyN  and 

<0.  C/Xi^i  =  CH 
NH 

Indol  is  one  of  the  many  putrefactive  x>roducts  of  the  decomposition  of  pro- 
teids.  Take  equal  parts  of  fi-esh  fibrin  and  finely-divided  ox-pancreas,  add 
ten  times  the  volume  of  water,  and  keep  the  whole  continuously  at  a  tempera- 
ture of  40°  C.  for  three  or  four  days.  Intensely  disagreeable-smelling  gases 
are  given  off.  Strain  through  linen,  acidulate  (acetic  acid),  and  distil  the 
filtrate.  The  filtered  distillate  is  made  alkaline  by  KHO  or  NaHO,  and 
shaken  thoroughly  with  its  own  volume  of  ether.  Distil  the  ether,  and  the  oily 
substance  which  remains  behind,  on  being  dissolved  in  water,  is  allowed  to 
crystallise.     The  solution  yields  the  following  tests. 

Tests  for  Indol. — Use  either  the  watery  solution  of  indol  or  the 
filtered  offensive-smelling  fluid  before  it  is  distilled. 

(a.)  "Warm  the  liquid,  and  add  first  a  drop  or  two  of  dilute 
sulphuric  acid  to  some  of  the  filtered  liquid,  and  then  a  very  dihife 
nitrite  solution.  A  red  colour  indicates  the  presence  of  indol.  This 
test  is  very  readily  obtained  with  the  products  of  digestion  by 
Kiihne's  dry  pancreas  (Lesson  X.  1,  e).  One  must  be  careful  to 
regulate  the  strength  of  the  acid,  as  too  strong  nitrous  acid  prevents 
the  reaction. 

(6.)  Acidify  strongly  with  hydrochloric  acid  a  small  quantity  of  the  highly 
offensive  fluid  or  the  watery  solution,  and  i)lace  in  it  a  shaving  of  wood,  or  a 
wooden  match  with  its  head  removed  and  soaked  in  strong  hydrochloric  acid. 
The  match  is  coloured  red,  sometimes  even  an  intense  red.  The  match  can  be 
dried,  and  it  keeps  its  colour  for  a  long  time,  although  the  colour  darkens 
and  becomes  somewhat  duskier  on  drying. 

(c.)  Chlorine  Reaction. — Add  to  some  of  the  digestive  fluid  (5, 
&,  preferably  digest  B),  drop  by  drop,  chlorine  water ;  it  strikes 
a  rosy-red  tint.  Or  add  very  dilute  bromine  Avater  (i  to  2  drops 
to  60  cc.  water),  the  fluid  first  becomes  pale  red,  then  violet,  and 
ultimately  deep  violet  (KUhne). 

7.  III.  The  Action  on  Fats  is  Twofold. 
(A.)  Emulsification. 

{a.)  Rub  up  in  a  mortar  which  has  been  warmed  in  warm  water 
a  little  olive-oil  or  melted  lard,  and  some  pieces  of  fresh  pancreas. 
A  creamy  persistent  emulsion  is  formed.  Examine  the  emulsion 
under  the  microscope.  Or  use  a  watery  extract  of  the  fresh  pan- 
creas, and  do  likewise ;  but  in  this  case  the  result  will  not  be  nearly 
so  satisfactory. 


84  PRACTICAL  PHYSIOLOGY.  [X. 

(/>.)  Rub  up  oil  as  in  (a.) ;  but  this  time  use  an  extract  of  the  fresh  pancreas 
made  witli  i  j)er  cent,  sodic  carbonate.  A  veiy  perfect  emulsion  is  obtained, 
even  if  the  sodic  carbonate  extract  is  boiled  beforehand.  This  shows  that  its 
emulsifying  power  does  not  depend  on  a  ferment. 

(c.)  The  presence  of  a  little  free  /(Uty  acid  greatly  favours  emidsification. 
Take  two  samples  of  cod-liver  oil,  one  perfcrHy  neutral  (by  no  means  easily 
procured),  and  an  ordinary  brown  o\\.—e.g.,  De  Jongh's.  The  latter  contains 
much  free  fatty  acid.  Place  5  cc.  of  each  in  two  test-tubes,  and  pour  on  them 
a  little  solution  of  sodic  carbonate  (i  per  cent.).  The  neutral  oil  is  not 
emulsified,  while  the  rancid  one  is  at  once,  and  remains  so.  Many  oils  that 
do  not  taste  rancid  contain  free  fatty  acids,  and  only  some  of  them  give  up 
their  acid  to  water,  just  according  as  the  fatty  acid  is  soluble  or  not  in  water. 

8.  (B.)  The  Fat-Splitting  Action  of  Pancreatic  Juice  (Steapsin 
or  pialyn,  the  ferment). 

(a.)  Prepare  a  Perfectly  Neutral  Oil. — A  perfectly  neutral  oil  is  required, 
and  as  all  commercial  oils  contain  free  fatty  acids,  they  must  not  be  used. 
Place  olive  or  almond  oil  in  a  porcelain  capsule,  mix  it  with  not  too  much 
baryta  solution,  and  boil  for  some  time.  Allow  it  to  cool.  The  unsaponified 
oil  is  extracted  with  ether,  the  ethereal  extract  separated  from  the  insoluble 
portion,  and  the  ether  evaporated  over  warm  water.  The  oil  should  now  be 
perfectly  neutral  {Krukcnhcrg). 

{b.)  Mix  the  oil  with  finely  divided,  perfectly  fresh  pancreas  (not  a  watery 
extract),  and  keep  it  at  40''  C.  After  a  time  its  reaction  becomes  acid,  owing 
to  tlie  formation  of  a  fatty  acid.  This  experiment  is  by  no  means  easy  to  per- 
form, and  some  observers  deny  altogether  the  existence  of  a  fat-splitting 
fennent.  The  free  fatty  acids  thus  liberated  unite  with  the  alkaline  bases  of 
bile,  and  form  soaps. 

9.  IV.  Milk-Curdling  Ferment. 

(a.)  Add  a  drop  or  Uvo  of  the  brine  extract  of  the  pancreas  pre- 
pared for  you  to  5  cc.  of  warm  milk  in  a  test-tube,  and  keep  it  at 
40°  C.  Within  a  few  minutes  a  soHd  coagulum  forms,  and  there- 
after the  whey  begins  to  separate. 

(A.)  Repeat  (a.),  but  add  a  grain  or  less  of  bicarbonate  of  soda  to 
the  milk.  Coagulation  occurs  just  as  before,  so  that  this  ferment 
is  active  in  an  alkaline  medium. 

(c.)  Boil  the  ferment  first.     Its  power  is  destroyed. 

10.  Action  on  Milk. 

(a.)  Place  cow's  milk  diluted  with  5  volumes  of  water  in  a  test- 
tube,  add  a  drop  or  two  of  pancreatic  extract  or  liquor  pancrea- 
ticiis.  Keep  at  40°  C.  for  half  an  hour.  The  caseinogen  is  first 
curdled  and  then  dissolved,  and  as  this  occurs,  the  milk  changes 
from  a  white  to  a  yellowish  colour. 

(/>.)  Divide  (a.)  into  two  portions,  A  and  B.  To  A  add  dilute 
acetic  acid ;  there  is  no  precipitation  of  caseinogen,  which  has  been 
converted  into  peptones.  To  B  add  caustic  soda  and  dilute  copper 
sulphate,  wliich  give  a  rose  colour,  proving  the  presence  of  peptones. 


X.]  PANCREATIC   DIGESTION.  85 

11.  To  Peptonise  Milk. — A  pint  of  milk  is  diluted  with  a 
quarter  of  a  pint  of  water,  and  heated  to  a  lukewarm  temperature, 
about  140°  F.  (60°  C).  Or  the  diluted  milk  may  be  divided  into 
two  equal  portions,  one  of  which  may  be  heated  to  the  boiHng- 
point  and  then  added  to  the  cold  portion,  the  mixture  will  then  be 
of  the  required  temperature.  Two  tea-spoonfuls  of  liquor  pancrea- 
ticus,  together  with  about  fifteen  grains,  or  half  a  level  tea-spoonful, 
of  bicarbonate  of  soda,  are  then  mixed  therewith.  The  mixture  is 
next  poured  into  a  jug,  covered,  and  placed  in  a  warm  situation  to 
keep  up  the  heat.  In  a  few  minutes  a  considerable  change  will 
have  taken  place  in  the  milk,  but  in  most  cases  it  is  best  to  allow 
the  digestive  process  to  go  on  for  ten  or  twenty  minutes.  The 
gradually  increasing  bitterness  of  the  digested  milk  is  unobjection- 
able to  many  palates ;  a  few  trials  will,  however,  indicate  the  limit 
most  acceptable  to  the  individual  patient ;  as  soon  as  this  point  is 
reached,  the  milk  should  be  either  used  or  boiled  to  prevent  further 
change.  From  ten  minutes  to  half  an  hour  is  the  time  generally 
found  sufficient.     It  can  then  be  used  hke  ordinary  milk. 


ADDITIONAL  EXERCISES. 

12.  Preparation  of  Indol.— Place  i  kilogram  of  fresh  fibrin  in  a  6-Iitre  jai 
with  4  litres  of  water  (to  which  i  gram  KH0PO4  and  .5  gram  MgSOj  are 
added).  Mix  this  with  200  cc.  cold  saturated  solution  of  sodic  carbonate,  and 
add  to  the  whole  a  quantity  of  putrefying  flesh-juice  and  some  pieces  of  the 
putrid  flesh  as  well.  Cork  the  vessel,  a  vent-tube  being  placed  in  the  cork, 
and  place  it  aside  fv^r  5-6  days  at  a  temperature  of  40-42°  C.  Distil  and 
acidify  the  strongly  ammoniacal  distillate  with  HCl,  add  some  copper 
sulphate,  and  filter.  Shake  up  equal  volumes  of  the  distillate  and  ether  in  a 
separation  funnel.  Allow  the  filtrate  to  settle,  run  it  off,  add  some  fresh 
filtrate,  and  shake  again  with  the  same  ether.  Distil  the  ethereal  extract  to 
about  one-fourth  of  its  volume,  shake  up  the  residue  very  thorouglily  with 
caustic  soda  (to  remove  phenol  and  traces  of  acids).  Distil  the  ether,  and 
after  the  addition  of  caustic  soda  distil  the  oily  indol.  The  distillate  is  shaken 
up  with  ether,  and  the  ethereal  extract  is  evaporated  at  a  low  temperature, 
when  crystals  or  plates  of  indol  separate.  This  preparation  usually  contains 
some  skatol.     {Drechsel  after  Salkowski.) 


Some  Nitrogenous  Derivatives  of  the  Fobegoing. 

13.  Leucin  or  a-Amido-isobutylacetic  acid,  C6Hi3N02  =  2(CH3)CH— CH2— 
CH(NH2)C0.0H,    and  Tyrosin   or    Paraoxyphenyl-a-Amidopropionic    acid, 

CyHjiN03=C6H4<^^(NH2)CO.  OH.— These    two    bodies     are    obtained 

together  from  nearly  all  proteids  when  the  latter  are  decomposed  by  the  action 
of  acids.  The  former  belongs  to  the  fatty  bodies,  and  tyrosin  to  the  aromatio 
group,  and  is  a  derivative  of  benzene  (CgHe). 


86 


PRACTICAL  PHYSIOLOGY. 


[X 


Preparation  of  Leucin  and  Tyrosin. — Place  2  parts  of  horn  shavings 
{h-i  kilo.)  in  a  mixture  of  5  parts  of  concentrated  sulphuric  acid  and  13  parts 
of  water.  Boil  for  twenty-four  hours  in  a  vessel  placed  in  connection  with  a 
condenser.  Add  thin  milk  of  lime  until  a  feebly  alkaline  reaction  is  obtained, 
filter  through  flannel,  re-extract  the  residue  with  water,  mix  the  filtrate  and 
washings  and  slightly  acidulate  them  with  oxalic  acid.  Filter  to  remove  the 
oxalate  of  lime,  and  evaporate  the  filtrate  until  a  scum  forms  on  the  surface. 
Cool  and  repeat  the  evaporation  process  until  crystallisation  ceases  to  take 

place  in  the  mother-fluid.  Collect  the 
mass  of  crystals,  dissolve  them  in  boiling 
water  with  the  addition  of  ammonia,  and 
add  lead  acetate  until  the  resulting  pre- 
cipitate is  no  longer  brown,  but  becomes 
white.  Filter,  acidulate  the  acid  filtrate 
feebly  with  dilute  sulphuric  acid,  filter  oft 
the  lead  sulphate  and  allow  the  fluid  to 
cool,  when  tyrosin  in  an  almost  pure  form 
crystallises  out. 

The  mother-liquor,  freed  from  tyrosin,  is 
treated  with  sulphuretted  hydrogen  to  get 
rid  of  the  lead,  filtered,  evaporated,  and 
boiled  for  a  few  minutes  with  freshly 
precipitated  hydrated  copper  oxide,  which 
Fig.  44.— Crystals  and  Sheaves  of  Tyrosin.  forms  a  dark  blue  solution.     The  latter, 

when  filtered  and  evaporated,  yields  blue 
crystals  and  an  insoluble  compound  of  leucin-copper  oxide.  This  deposit  and 
the  crystals  are  decomposed  in  water  by  H.^S- solution,  the  filtrate  when 
necessary  decolorised  by  boiling  with  animal  charcoal,  again  filtered  and 
evaporated  to  crystallisation,  when  leucin  crystallises  out.  It  is  obtained 
pure  by  recrystallisation  from  boiling  alcohol  {Drecltsel). 


14.  Tyrosin  is  insoluble  in  alcohol  and  in  1000  parts  of  cold  water. 

(a.)  Observe  microscopically  its  crystalline  form,  as  fine  long  silky  needles 
arranged  in  sheat-like  bundles  (fig.  44). 

{b.)  Boil  a  hot  watery  solution  with  Millon's  reagent  (avoid  excess)  =  a  red 
colour  {Hoffman's  test). 


15.  Leucin. — (o.)  Under  the  microscope  observe  it  in  the  form  of  brown 
balls,  with  radiating  and  concentric  lines  it  it  is  impure  ;  and,  when  it  is 
pure,  as  white  shining  lamellne,  with  a  fatty  glance.  It  is  soluble  in  27  parts 
of  cold  water,  and  much  less  soluble  in  alcohol, 

(6.)  Heated  in  a  tube  it  sublimes  unchanged  in  very  fine  clouds  with  tha 
odour  of  amylamine.     A  part  is  decomposed  into  COg  and  CjHjaN  (amylamine). 


XI.]  THE  BILE.  87 

LESSON  XI. 
BILE. 

1.  Use  ox-bile  obtained  from  the  butcher,  and,  if  possible,  human 
bile. 

(a.)  The  colour  in  man  is  a  brownish-yellow,  in  the  ox  greenish, 
but  often  it  is  reddish-brown  when  it  stands  for  a  short  time, 
Note  its  bitter  taste,  pecuHar  smell,  and  specific  gravity  (loio- 
1020). 

(b.)  It  is  alkaline  or  neutral  to  litmus  paper. 

(c.)  Pour  some  ox-bile  from  one  vessel  to  another,  and  note  that 
strings  of  so-called  mucin  connect  one  vessel  with  the  other. 

{d.)  Acidulate  bile  with  acetic  acid,  which  precipitates  mucinoid 
substance  coloured  with  pigments.  Filter  off  this  precipitate.  Test 
the  filtrate. 

(e.)  It  gives  no  reactions  for  albumin. 

(/".)  Add  hydrochloric  acid  and  potassic  ferrocyanide.  A  blue 
colour  indicates  the  presence  of  iron.  Test  for  chlorides  and  other 
salts. 

{(/.)  Fresh  human  bile  gives  no  spectrum,  although  the  bile  of 
the  ox,  mouse,  and  some  other  animals  does. 

2.  Bile-Salts  or  Bilin  (glycocholate  and  taurocholate  of  sodium). 
(a.)  Concentrate  ox-bile  to  one-fourth  of   its  bulk,   mix  with 

animal  charcoal  in  a  mortar  to  form  a  thick  paste.     Evaporate  to 
complete  dryness  over  a  water-bath. 

(b.)  To  the  dry  charcoal-bile  mixture,  add  five  volumes  of  abso- 
lute alcohol.  Shake  the  mixture  from  time  to  time,  and  after  half 
an  hour  filter.  To  the  filtrate  add  much  ether,  which  gives  a 
white  precipitate  of  the  bile-salts.  If  no  water  be  present,  some- 
times the  bile-salts  are  thrown  down  crystalline;  but  not  unfre- 
quently  they  go  down  merely  as  a  milky  opalescence,  which  quickly 
forms  resinous  masses.  It  is  best  to  allow  the  mixture  to  stand 
for  a  day  or  two,  to  obtain  the  glancing  needles  which  constitute 
Plattner's  Crystallised  Bile. 

Scheme  for  Bile-Salts ,  etc, 

200  cc.  of  ox-bile,  dried,  mixed  with  animal  charcoal,  are  extracted  with 
absolute  alcohol  by  the  aid  of  heat ;  filter. 

Residue,  rmicin,  Alcoholic  solution  treated  with 

pigments,  salts,  charcoaL  ether. 

Precipitate,  Solution  contains 

Bile-salts.  Cholesteriv. 


88  PRACTICAL  PHYSIOLOGY.  [XL 

3.  Pettenkofer's  Test  for  Bile- Acids  (Salts)  and  Cholic  Acid. 

(a.)  To  bile  in  a  test-tube,  add  a  drop  or  two  of  syrup  of  cane- 
sugar.  Pour  in  concentrated  sulphuric  acid,  at  the  hue  of  junction 
of  the  two  fluids  a  purple  colour  is  obtained.  Furfuraldehyde  is 
formed  from  the  action  of  sugar  and  sulphuric  acid,  and  the  purple 
compound  is  due  to  the  aldehyde  compound  with  cholalic  acid.  The 
white  deposit  seen  above  the  Hne  of  junction  is  precipitated  bile- 
acids.     They  are  insoluble  in  water. 

(/;.)  A  better  way  of  doing  the  test  is  as  follows : — After  mixing 
the  bile  and  syrup,  shake  the  mixture  until  the  upper  part  of  the 
tube  is  filled  with  froth.  Pour  sulphuric  acid  down  the  side,  and 
a  purple-red  colour  is  struck  in  the  froth. 

(c.)  Make  a  film  of  bile  on  a  porcelain  capsule,  add  a  drop  of  syrup 
of  cane-sugar,  and  then  a  drop  of  sulphuric  acid  =  purple  colour. 

(d.)  Or,  after  mixing  the  syrup  with  the  bile,  add  the  strong  sulphuric  acid 
drop  by  drop,  mixing  it  thoroughly.  Heat  gently,  and  the  fluid  becomes  a 
deep  purple  colour.  Take  care  not  to  add  too  much  syrup,  and  not  to  over- 
heat the  tube.  If  the  requisite  amount  of  sulphuric  acid  be  added,  the  tem- 
perature becomes  sufficiently  high  (70°  C.)  without  requiring  to  heat  the  tube. 

(e.)  Strassburger's  Modification  (e.g.,  for  bile  in  urine). — To  the  urine  add 
a  little  syrup  and  mix.  Dip  filter-paper  into  the  fluid  and  dry  the  paper. 
On  placing  a  drop  of  sulphuric  acid  on  the  latter,  after  some  time  a  purple 
spot  which  has  eaten  into  the  paper  is  observed. 

( f. )  Repeat  any  or  all  of  the  above  processes  with  a  watery  solution  of  the 
bile-salts  and  with  acid  albumin. 

(g.)  In  place  of  sugar  furfurol  (Mylius)  may  be  used.  Add  i  drop  of  fur- 
furol  solution  (i  per  1000)  and  i  cc.  of  concentrated  H0SO4. 

4.  Similar  purple  colour  reactions  are  obtained  with  many  other  sub- 
stances— e.g.,  albumin  and  a-naphthol,  but  the  spectra  differ  somewhat. 

Albumin  and  Sulphuric  Acid, — To  a  solution  of  acid-albumin  and  syrup 
add  strong  sulphuric  acid,  a  similar  tint  is  obtained.  The  spectra,  however, 
are  diff"erent,  the  red-purple  fluid  from  bile  gives  two  absorption-bands,  one 
between  E  and  F,  and  another  between  D  and  E.  In  the  albuminous  solu- 
tions only  one  absorption-band  exists  between  E  and  F. 

5.  Action  of  Bile  or  Bile-Salts  in  Precipitating  Sulphur. 

(a.)  In  one  beaker  (A)  place  diluted  bile  and  in  the  other  (B)  water.  Pour 
flowers  of  sulphur  on  both.  The  sulphur  falls  in  a  shower  through  the  fluid 
of  A,  while  none  passes  through  B. 

(b.)  Test  to  what  extent  bile  may  be  diluted  before  it  loses  this  property, 
which  is  due  to  the  diminution  of  the  surface  tension  by  the  bile-salts  {M.  Hay). 

(c.)  Repeat  with  a  solution  of  the  bile-salts. 

Bile-Pigments.— The  chief  are  bilirubin  (red),  biliverdin  (green), 
and  urobilin. 

6.  Gmelin's  Test  for  Bile-Pigments. 

{a.)  Place  a  few  drops  of  bile  on  a  white  porcelain  slab.  With 
a  glass  rod  place  a  drop  or  two  of  strong  nitric  acid  containinr/ 
nitrous  acid  near  the  drop  of  bile,  bring  the  acid  and  bile  into 
contact.  Notice  the  play  or  succession  of  colours,  beginning  with 
gi'een  and  passing  into  blue,  red,  and  dirty  yellow. 


«.] 


THE   BILE. 


89 


(b.)  Place  a  little  impure  nitric  acid  in  a  test-tube.  Slant  the  tube  and 
pour  in  bile,  a  similar  play  of  colours  occurs — green  above,  blue,  red,  and 
yellow  below.  It  is  better  to  do  this  reaction  after  removal  of  the  mucin  by 
acetic  acid  (Lesson  XL  1,  d).  Or  add  the  nitric  acid,  and  shake  after  the 
addition  of  every  few  drops  ;  the  successive  colours  from  green  to  yellow  are 
obtained  in  great  beauty.    For  a  modification  applicable  to  urine,  see  "  Urine." 

(c.)  To  green  bile  +  amm.  sulphide  and  shake  =  reduction  to  bilirubin. 

("'.)  To  yellow  bile  +  KHO  and  heat,  acidulate  with  HCl  =  green  due  to 
oxidation  of  bilirubin. 


Fig.  45.— Crystals  of 
Cholesterin. 


7.  Cholesterin  and  Gall-Stones. 

('/.)  Preparation. — Powder  a  gall-stone  and  extract  it  with  ether 
or  boiling  alcoliol.  Heat  the  test-tube  in  warm  water,  and  see  that 
no  gas  is  burning  near  it.  Drop  the  solution 
on  a  glass-slide,  and  examine  the  crystals  micro- 
scopically. They  are  flat  plates,  with  an  oblong 
piece  cut  out  of  one  corner  (fig.  45).  Ethereal 
solution  gives  needles,  but  a  hot  alcoholic  solution 
gives  the  typical  plates. 

(b.)  Heat  crystals  in  a  watch-glass  with  a  few  drops 
of  moderately  strong  sulphuric  acid,  and  then  add 
iodine  ;  a  play  of  colours,  passing  through  violet,  blue, 
green,  red,  and  brown,  occurs. 

(c.)  Dissolve  crystals  in  chloroform,  add  an  equal 
volume  of  covcenLrated  sulphuric  acid,  and  shake  the 
mixture.  When  the  chloroform  solution  floats  on  the 
top,  it  becomes  blood-red,  but  changes  quickly  on  exposure  to  the  air,  passing 
tlirough  violet  and  blue  to  green  and  yellow.  A  trace  of  water  decolorises 
it  at  once.     The  layer  of  sulphuric  acid  shows  a  green  fluorescence. 

{(l.)  The  crystals  when  acted  on  by  strong  sulphuric  acid  become  red.  Do 
this  on  a  slide  under  the  microscope. 

{c.)  Examine  microscopically  crystals  of  cholesterin  found  in  hydrocele  fluid. 
The  crystals  may  not  be  quite  perfect,  but  their  characters  are  quite  distinct. 

8.  Action  of  Bile  in  Digestion, 

{a,)  Action  on  Starch. — Test  if  bile  converts  starch  mucilage 
into  a  reducing  sugar,  as  directed  for  saliva  (Lesson  VIII.). 

{!).)  Action  on  Fats. — Mix  thoroughly  10  cc.  bile  with  2  cc. 
almond-oil,  and  observe  both  by  the  naked  eye  and  the  microscope 
to  what  extent  emulsion  occurs,  and  how  long  it  lasts.  Compare 
a  similar  mixture  of  oil  and  water.  In  the  former  case  a  pretty  fair 
emulsion  will  be  obtained.  In  the  latter  the  oil  and  water  separate 
rapidly. 

(c)  Mix  10  cc.  of  bile  with  2  cc.  of  almond-oil,  to  which  some  oleic  acid  is 
added.  Shake  well,  and  keep  the  tube  in  a  water-bath  at  40°  C.  A  very 
good  emulsion  is  obtained.  The  bile  dissolves  the  fatty  acids,  and  the 
latter  decompose  the  salts  of  the  bile-acids  ;  the  bile-acids  are  liberated,  while 
the  fatty  acid  unites  with  the  alkali  of  the  bile-salts  to  form  a  soap.  The 
soap  is  soluble  in  the  bile,  and  serves  to  increase  the  emulsifying  power,  as  an 
emulsion  once  formed  lasts  much  longer  in  a  soapy  solution  than  in  water. 


go  PRACTICAL   PHYSIOLOGY.  [XI. 

(rf.)  Favours  Filtration  and  Absorption. — Place  two  small  fiinnels  ex- 
actly the  same  size  in  a  filter-stand,  and  under  each  a  beaker.  Into  each 
funnel  put  a  filter-paper  ;  moisten  the  one  witli  water  (A),  and  the  other  with 
bile  (B) ;  pour  into  both  an  equal  volume  of  almond-oil ;  cover  with  a  slip  ol 
glass  to  prevent  evaporation.  Set  aside  for  twelve  hours,  and  note  that  the 
oil  passes  through  B,  but  scarcely  any  through  A. 

(c.)  Effect  on  the  Proteid  Products  of  Crastric  Digestion.  — Digest  some 
fibrin  in  artificial  gastric  juice,  filter,  and  to  the  filtrate  add  drop  by  drop 
ox-bile,  or  a  solution  of  bile-salts.  It  causes  a  white  precipitate  of  pe})tones 
and  acid-albumin.  The  acid  of  the  gastric  juice  splits  up  the  bile-salts,  so 
that  the  bile-acids  are  also  thrown  down. 

(/. )  Action  on  Acid- Albumin.  —  Prepare  acid-albumin  in  solution  (Lesson 
I.),  and  add  a  few  drops  of  bile — be  careful  not  to  add  too  much — or  bile-salts. 
This  causes  curdling  of  the  whole  mass.  In  {e.)  and  (/. )  it  is  better  to  add 
bile-salts,  because  ft-ee  hydrochloric  acid  gives  a  precipitate  with  bile. 


ADDITIONAL  EXEECISEfS. 

9.  Preparation  of  Taurin  (;8-amidooethyl-sulphuric  acid  C2H7NSO3).  — 
Mix  ox-bile  with  an  excess  of  strong  hydrochloric  acid,  filter  from  the  slimy 
deposit,  and  evaporate  the  mixture— just   under  boiling-point— whereby  a 

tough  brownish  resinous  body  separ- 

^^^■p^/^    """^^''l^^'E  a-tes— choloidinic  acid.      Pour  oil  the 
^HH|^  _i^^m   acid  watery  fluid,  concentrate  it  still 

«g|^P*^-r-"       -  -         jK7    f^p^2;^gj.^  until  the  greater  part  of  the 

^H^la,>,  ,  ,1 >T  ,,>-   's^     common   salt    crystallises    out.      Mix 

^tS^i'^wxmisi'^M/       the  cold    mother-liquid   with    stiong 

^SKkKHKO/  alcohol,  whereby  taurin  is  j)recipitated 

^^S^jmUB^^  along  with  some  common  salt.     Wash 

^^^^^^HRj^^  the  precipitate  with  alcohol,    dry  it, 

-^^^^^TMtfTT^y  ^^^  dissolve  it  in  a  small  quantity  of 

.^^^^R  wwlwlW  boiling    water.      On    cooling,    taurin 

^^^^  will™'  separates  in  four-sided  prisms. 

^^1^^  10.    Cholesterin.  —  Boil    powdered 

If  pale     gall-stones  in  water,    and   then 

Fig.  46.— Double-Walled  Filter  for  Filtering  extract    them    with    boiling    alcohol. 

Hot  Solutions.  Filter  through  a  double-walled   filter 

kept  hot  with  boiling  water  (fig.  46). 

The  filtrate  on  cooling  precipitates  impure  cholesterin.     Recrystallise  it  from 

boiling  alcohol    containing    potash,    wash  it  with  alcohol   and   water,    and 

dry  the  residue  over  sulphuric  acid  (fig.  16). 

Scheme  for  Gail-Stones  (Salkowski). 

Powdered  gall-stones  are  extracted  with  ether  ;   filter. 

I 


Solution  evaporated                                             Residue  (B)  treated  on  the 
Cholesterin  (A).                                                     filter  with  dilute  HCl. 
L. 

Solution  (C)  Idme  saZU,  Residue  (D)  washed  with  water, 

dried,  treated  with  chloroform  ; 
Bilirubin.  \ 


xil]  glycogen  in  the  liver.  $i 


LESSON  XII. 
GLYCOGEN  IN  THE  LIVER. 

1.  Preparation. 

(a.)  Feed  a  rabbit  on  carrots  for  a  day  or  longer,  or  a  rat  on 
oatSj  and  five  or  six  hours  after  the  last  meal  decapitate  it  or  kill 
it  by  bleeding.  Rapidly  open  the  abdomen,  remove  the  liver,  cut  one 
half  of  it  in  pieces,  and  throw  it  into  boiUng  water  slightly  acidu- 
lated with  acetic  acid.  Lay  the  other  half  aside,  keeping  it  moist 
in  a  warm  place  for  some  hours.  After  boiling  the  first  portion 
for  a  time,  pound  it  in  a  mortar  with  sand,  and  boil  again.  Filter 
while  hot.  The  filtrate  is  milky  or  opalescent,  and  is  a  watery 
solution  of  glycogen  and  other  substances.  The  acetic  acid  co- 
agulates the  proteids,  while  the  boiling  water  destroys  either  a 
ferment  in  the  liver  or  the  liver  cells,  which  would  convert  the 
glycogen  into  grape-sugar. 

(/>.)  Brticke's  Method. — Feed  a  rabbit  on  carrots,  and  after 
five  or  six  hours  kill  it  by  bleeding.  Open  the  abdomen,  rapidly 
remove  the  liver.  Some  wash  out  its  blood-vessels  with  a  stream 
of  normal  saline.  Divide  it  into  two  portions.  Cut  one  half  as 
rapidly  as  possible  into  small  pieces,  and  throw  the  pieces  into 
boiling  water. 

Boil  them,  and  afterwards  pound  them  in  a  mortar  and  boil 
again.  Filter  while  hot,  and  observe  the  opalescent  filtrate,  which 
is  a  solution  of  glycogen  and  proteids.  The  filtrate  should  flow 
into  a  cooled  beaker,  placed  in  a  mixture  of  ice  and  salt.  Pre- 
cipitate the  proteids  by  adding  alternately  hydrochloric  acid  and 
potassio-mercuric  iodide  (p.  93),  until  all  the  proteids  are  pre- 
cipitated. Filter  off*  the  proteids,  and  the  opalescent  filtrate  is  an 
imperfect  solution  of  glycogen.  To  separate  the  (jlycogen.  Evapor- 
ate the  fluid  to  a  small  bulk,  and  precipitate  the  glycogen  by 
adding  96  per  cent,  alcohol  until  the  solution  contains  over  60  per 
cent,  of  alcohol.  The  glycogen  is  precipitated  as  a  white  flocculent 
powder,  which  is  collected  on  a  filter,  washed  with  alcohol  and 
ether,  and  then  dried  in  an  oven  at  100°  G.  (fig.  47). 

(c.)  Kulz's  Method. — Feed  a  rabbit  for  two  days  on  carrots  or  boiled 
rice.  Five  or  six  hours  after  the  last  full  meal  decapitate  it,  open  tlie 
abdomen,  rapidly  remove  the  liver  (weigh  it),  cut  it  quickly  into  pieces,  and 
throw  the  latter  into  a  large  porcelain  capsule  (400  cc.  water  to  100  grama 
liver)  of  water  boiling  briskly.  Boil  the  pieces  for  about  half  an  hour.  Re- 
move the  pieces,  rub  them  up  into  a  pul])  in  a  mortar  (this  may  be  aided  by 


92 


PRACTICAL   PHYSIOLOGY. 


[XIL 


rubbing  with  well  washed  white  sand).  Replace  the  pulp  in  the  boiling  water 
and  add  3-4  grams  of  caustic  potash  {i.e.,  for  100  grams  liver).  Heat  on  a 
water-bath  and  evaporate  until  about  203  cc.  of  fluid  remains  for  100  grams 
liver.  If  a  pellicle  fonns  on  the  surfiice,  heat  the  whole  in  a  beaker  covered 
with  a  watch-glass  until  the  pellicle  is  dissolved.  Allow  to  cool.  Neutralise 
with  dilute  liydrochloric  acid  and  precipitate  the  })roteids  by  adding  alter- 
nately hydrochloric  acid  and  potassio  mercuric  iodide  in  small  quantities, 
until  no  further  precipitation  occurs.  Filter  through  a  thick  filter  to  remove 
the  deposit  of  proteids.  Remove  the  deposit  from  the  filter  with  a  spatula, 
and  rub  it  up  in  a  mortar  with  water  containing  hydrochloric  acid  and 
potassio  mercuric  iodide,  and  again  filter  the  pulp.  Repeat  this  process 
several  times  to  get  out  all  the  glycogen.  Mix  the  filtrates  and  add  2  volumes 
of  96  per  cent,  alcohol,  stirring  briskly  all  the  time  ;  this  precipitates  the 
glycogen.  Allow  it  to  stand  in  a  cool  place  for  a  night ;  filter,  and  wash  the 
precipitate  thoroughly,  first  with  62  per  cent,  and  then  with  96  per  cent. 


Fig.  47. — Hot-Air  Oven.     O.  Gas  regulator  ;  E.  Thermometer. 

alcohol.  Usually  the  glycogen  contains  a  trace  of  albumin.  To  remove  the 
latter,  redissolve  the  moist  glycogen  in  warm  water,  and  after  cooling,  repre- 
cipitate  with  HCl  and  potassiomercuric  iodide  and  proceed  as  above.  Wash 
the  glycogen  with  alcohol  and  then  with  ether,  and  dry  it  by  exposure  to  the 
air.     This  method  gives  the  most  satisfactory  results. 

{d.)  Instead  of  a  rat  or  rabbit's  liver,  use  oysters  or  the  edible  mussel,  and 
prepare  a  solution  of  glycogen  by  methods  {a. )  or  (*.). 

(e.)  Use  the  other  half  of  the  liver  of  the  rat  or  rabbit  that  has 
been  kept  warm,  and  make  a  similar  extract  of  it. 

2.  Precipitate  the  Glycogen.— Evaporate  the  filtrate  of  (a.)  or 
(&.)  to  a  small  bulk,  and  precipitate  the  glycogen  as  a  white 
powder  by  adding  a  large  amount  of  alcohol — at  least  60  per  cent. 


XII.]  GLYCOGEN   IN   THE   LIVER.  93 

must  be  added.  Filter;  wash  the  precipitate  on  the  filter  with 
absolute  alcohol  and  ether,  and  dry  it  over  sulphuric  acid  or  in  a 
hot-air  oven  (fig.  47). 

3.  Preparation  of  Potassio-Merciiric  Iodide  or  Briicke's  Reagent. — Pre- 
cipitate a  saturated  solution  of  potassic  iodide  with  a  similar  solution  of 
mercuric  chloride  ;  wash  the  precipitate,  and  dissolve  it  to  saturation  in  a  hot 
solution  of  potassic  iodide. 

4.  Tests  for  Glycogen. 

(a.)  To  the  opalescent  filtrate  add  iodine  solution  =  a  port  wine 
red  or  mahogany-brown  colour  (Hke  that  produced  by  dextrin). 
If  much  glycogen  be  present  the  colour  disappears,  and  more  iodine 
has  to  be  added.  Heat  the  fluid;  the  colour  disappears,  but  re- 
appears on  cooUng. 

A".^.— In  performing  this  test,  make  a.  control- experiment.  Take  two  test- 
tubes,  A  and  B.  In  A  place  glycogen  solution  ;  in  B,  an  equal  volume  of 
water.  To  both  add  the  same  amount  of  iodine  solution.  A  becomes  red, 
while  B  is  faint  yellow. 

(b.)  To  another  portion  add  lead  acetate  =  a  precipitate  (unlike 
dextrin).  The  solution  must  be  free  from  proteids  and  mercuric 
salts. 

(f.)  To  another  portion  add  lead  acetate  and  ammonia ;  the 
glycogen  is  precipitated  (like  dextrin). 

(d.)  Test  a  portion  of  the  glycogen  solution  for  grape-sugar.  There  may  be 
none,  or  only  the  faintest  trace. 

(e.)  To  a  ])ortion  (A)  of  the  glycogen  solution  add  saliva  or  liquor 
pancreaticus,  and  to  another  portion  (B)  add  blood,  and  place  both  in  a 
water-bath  at  40^  C.  After  ten  minutes  test  both  for  sugar.  (A)  will  be 
transparent,  and  give  no  reaction  with  iodine.  Perhaps  both  will  give  the 
sugar  reaction;  but  certainly  (A)  will,  if  care  be  taken  that  the  solution  is 
not  acid  after  adding  the  saliva.  The  ptyalin  converts  the  glycogen  into  a 
reducing  sugar. 

( ;'.)  Boil  some  glycogen  solution  with  dilute  hydrochloric  acid  in  a  flask  ; 
neutralise  with  caustic  soda,  and  test  with  Fehlings  solution  for  sugar. 

5.  Test  the  watery  extract  of  the  other  half  of  the  liver. 
(a.)  Perhaps  no  glycogen  reaction,  or  only  a  slight  one. 
(h.)  It  contains  much  reducing  sugar. 

6.  Extract  of  a  Dead  Liver. 

(a.)  Mince  a  piece  of  liver  from  an  animal  which  has  been  dead 
for  24  hours.  Boil  the  liver  either  in  water  or  a  saturated  solution 
of  sodic  sulphate.  Filter;  the  filtrate  is  clear  and  yellowish  in 
tint,  but  not  opalescent. 

(h.)  Its  reaction  is  acid  to  litmus  paper. 


94 


PRACTICAL  PHYSIOLOGY. 


[XIIL 


(r.)  Test  with  iodine  after  neutralisation  with  sodic  carbonate 
and  filtration  =  no  glycogen. 

('/.)  Test  for  grape-sugar  ^  much  sugar. 

After  death  the  glycogen  is  transformed  into  grape-sugar  unless 
precautions  be  taken  to  prevent  this  transformation  (p.  91). 


LESSON"  XIIL 


MILK,  FLOUR,  AND  BREAD. 

1.  Milk. — Use  fresh  cow's  milk. 
(a.)  Examine  the  "  naked-eye  "  characters  of  milk. 
(h.)  Examine  a  drop  of  milk  microscopically,  noting  numerous 
small,  higlily-refractive  oil-globules  floating  in  a  fluid  (fig.  48). 

(i.)  Add  dilute  caustic  soda.     The  globules  run  into  groups, 
(ii.)  To  a  ft-esh  drop  add  osmic  acid.     The  globules  first  become  brown  and 
then  black. 

(iii.)  If  a  drop  of  colostrum   is  obtainable,  observe   the    "colostrum  cor- 
puscles "  (fig.  48,  C). 

(c.)  Test  its  reaction  with 
Htmus  paper.  It  is  usually 
neutral  or  slightly  alkaline. 
{d.)  Take  the  specific  gra- 
M  vity  of  perfectly  fresh  un- 
skimmed milk  with  the 
lactometer.  It  is  usually  be- 
tween 1 028-1 034.  Take  the 
specific  gravity  next  day  after 
the  cream  has  risen  to  the 
surface,  or  after  the  cream 
is  removed.  The  specific 
gravity  is  increased  (1033-37) 
by  the  removal  of  the  lightest 
constituent — the  cream. 

(e.)  Dilute   milk    with   ten 

FlO.  48.— Microscopic  Appearance  of  Milk.    Tlie  times     its     volume     of     Water, 
upper  half,  if,  ia  milk;  the  lower  half,  colos-  r   ■,-,  i.     r  -i.     ,   -^-u 

trum,  c.  carefully    neutralise    it    with 

dilute  acetic  acid,  and  observe 
that  at  first  there  is  no  precipitate,  as  the  caseinogen  is  prevented 
from  being  precipitated  by  the  presence  of  alkaline  phosphates 
(Lesson  I.).     Cautiously  add  acetic  acid  until  there  is  a  copious 


xitl]  milk,  flour,  and  bread.  95 

granular-looking  precipitate  of  caseinogen,  which,  as  it  falls, 
entangles  the  greater  part  of  the  fat  in  it.  Precipitation  is  hastened 
by  heating  to  70°  C. 

(/.)  Filter  {e.)  through  a  moist  plaited  filter.  Keep  the  residue 
on  the  filter.  The  filtrate  is  clear.  Divide  it  into  two  portions. 
Take  one  portion,  divide  it  into  two,  and  boil  one  =  a  pre- 
cipitate of  lactalbumin  (serum-albumin).  Filter,  and  keep  the 
filtrate  to  test  for  sugar.  To  the  remainder  add  potassic  ferro- 
cyanide,  which  also  precipitates  serum-albumin. 

{g.)  Test  the  second  half  of  the  filtrate  for  milk-sugar.  Instead 
of  proceeding  thus,  test  for  the  presence  of  a  reducing  sugar  with 
the  filtrate  of  (/.)  after  the  separation  of  the  serum-albumin. 

(A.)  Scrape  off  the  residue  of  casein  and  fat  from  the  filter  (/. )  ;  wash  it  with 
water  from  a  wash-bottle,  and  exhaust  the  residue  with  a  mixture  of  ether 
and  alcohol.  On  placing  some  of  the  ethereal  solution  on  a  slide,  and  allowing 
it  to  evaporate,  a  greasy  stain  of  fat  is  obtained. 

{i.)  To  fresh  milk  add  a  drop  of  tincture  of  guaiacum,  which  strikes  a  blue 
colour  ;  boiled  milk  is  said  not  to  do  so. 

Separation  of  the  Chief  Constituents  of  Milk  (Salkowski). 
Milk  diluted  with  water,  precipitated  with  acetic  acid  and  filtered. 

I  I 

Filter-residue  (A)  (Caseinogen  Filtrate  (B),  (lact-albumin,  milk- 

+  Fat).     Extract  with  sugar,  salts),  concentrated  by 

Ether.  evaporation. 

i i    . 

I  II  I  ' 

Residue :  Solution  Coagulated  Further  eva])orated 

Caseinogen,  still  evaporated  Albumin  (E).       Calcic  'pho^ythate,   (F), 

with  JFat  (C).  Butter  fat  (D).  Milk  sugar  (G). 

2.  Separation  of  Caseinogen  by  Salts.— Saturate  milk  with 
magnesium  sulphate  or  sodium  chloride. 

The  caseinogen  and  fat  separate  out,  rise  to  the  surface,  and  leave 
a  clear  fluid  beneath.  Caseinogen,  like  globulins,  is  precipitated  by 
saturation  with  NaCl,  or  IMgSO^,  but  it  is  not  coagulated  by  heat. 
It  was  at  one  time  supposed  to  be  an  alkali-albumin,  but  the  latter  is 
not  coagulated  by  rennet.  It  appears  to  be  a  nucleo-albumin  (?), 
^.<'.,  a  compound  of  a  proteid  with  nuclein,  the  latter  a  body  rich  in 
phosphorus. 

Precipitation  of  Caseinogen  by  MgSO^. 


I  I 

Filter  residue  Filtrate  :  Milk,  sugar, 

Fat -f  Caseinogen.  albumin,  salts. 

Collect  the  precipitate  of  caseinogen  and  fat  on  a  filter  and  wash  it  with  a 


96  PRACTICAL   PHYSIOLOGY.  [XIIT 

saturaterl  solution  of  MgSOj.  Add  distilled  water,  which  in  presence  of  the 
MgS04  dissolves  the  caseinogen,  which  })asses  through  the  filter  and  is  col- 
lected. From  the  solution  of  caseinogen  in  weak  MgSO^  precipitate  the 
caseinogen  by  excess  of  acetic  acid.  To  get  the  caseinogen  quite  pure  it  must 
be  redissolved  in  weak  alkali  or  lime  water,  and  precipitated  and  rcdissolved 
several  times. 

Tlie  filtrate  after  proci})itation  of  caseinogen  contains  the  lactalbumin,  and 
can  be  completely  precipitated  by  saturation  with  sodium  sulphate.  It  coagu- 
lates between  70"  and  80'  C,  and  does  not  seem  to  be  separated  into  several 
proteids  by  fractional  heat  coagulation. 

The  fluid  contains  lactose,  salts,  and  serum-albumin.     Filter. 

3.  Separation  of  Caseinogen  and  Fat  by  Filtration. — Using  a  Bunsen's 
pump,  filter  milk  through  a  porous  cell  of  porcelain.  The  particulate  matters — 
caseinogen  and  fat— remain  behind,  while  a  clear  filtrate  containing  the  other 
substances  passes  through.  The  porous  cell  is  left  empty 
and  fitted  with  a  caoutchouc  cork  with  two  glass  tubes 
tightly  fitted  into  it.  One  tube  is  closed  with  a  clij)  (fig.  49), 
and  the  other  is  attached  to  the  pump  Place  the  ])orous 
cell  in  an  outer  vessel  containing  milk.  On  exhausting 
the  ])orous  cell  a  clear  watery  fluid  slowly  passes  through. 
Test  it  for  proteids  and  sugar.  Notice  the  absence  of  fat 
and  caseinogen. 

4.  Souring  of  Milk. — Place  a  small  quantity 
of  milk  in  a  vessel  in  a  warm  place  for  several 
days,  when  it  turns  sour  and  curdles.     It  becomes 

Fio  —Porous  Cell  ^^^^ — ^^^^  *^^^^  (Lessou  IX.  10) — iiaving  under- 
for"*  the  Filtration  gone  the  lactic  acld  fermentation,  the  lactose 
of  Milk.  being  split  up  by  a  micro-organism  into  lactic  acid. 

5.  Butter. — Place  a  little  milk  in  a  narrow,  cylindrical,  stoppered 
bottle  ;  add  half  its  volume  of  caustic  soda  and  some  ether,  and  shake 
the  mixture.  Put  the  bottle  in  a  water-batli  at  a  low  temperature  ; 
the  milk  loses  its  wjiite  colour,  and  an  ethereal  solution  of  the  fats 
floats  on  the  surface.  On  evaporating  the  ethereal  solution,  the 
butter  is  left  behind. 

6.  Curdling  of  Milk. 

(a.)  By  an  Acid. — Place  some  milk  in  a  flask ;  warm  it  to  40° 
C,  and  add  a  few  drops  of  acetic  acid.  The  mass  clots  or  curdles, 
and  separates  into  a  solid  curd  (caseinogen  and  fat),  and  a  clear 
fluid,  the  whey,  which  contains  the  lacto.se.     Filter. 

(h.)  By  Rennet  Ferment.— Take  5  cc.  of  fresh  milk  in  a  test- 
tube,  heat  it  in  a  water-bath  to  40°  C,  and  add  to  it  a  small 
quantity  of  extract  of  rennet,  or  an  equal  volume  of  a  glycerin 
extract  of  the  gastric  mucous  membrane,  which  has  been  neutral- 
ised with  dilute  sodic  carbonate,  and  place  the  tube  again  in  the 
water-bath  at  40°  C. 

Observe  that  the  whole  mass  curdles  in  a  few  minutes,  so  that 


XIII.]  MILK,  FLOUR,   AND   BREAD.  97 

the  tube  can  be  inverted  without  the  curd  falling  out.  By-and-by 
the  curd  shrinks,  and  squeezes  out  a  clear  slightly-yellowish  fluid, 
the  whey.     Filter. 

(6".)  Using  commercial  rennet  extract,  repeat  (b.),  but  boil  the 
rennet  first ;  it  no  longer  effects  the  change  described  above.  The 
rennet  ferment  is  destroyed  by  heat. 

(d,)  Boil  the  milk  and  allow  it  to  cool,  then  add  rennet ;  in  all 
probability  no  coagulation  will  take  place.  Boiled  milk  is  far  more 
difficult  to  coagulate  with  rennet  than  unboiled  milk. 

(e.)  Take  some  of  the  curd  of  6  (a.).  Dissolve  one  part  in  caustic 
soda  and  the  other  in  lime-water.  Add  rennet  to  both,  warm  to 
40°  C.  The  lime  solution  coagulates,  the  soda  solution  does  not. 
(The  ferment  of  rennet  has  been  called  rennin.) 

7.  The  Salts. 

(a.)  Using  the  filtrate  of  6  (a.),  add  magnesia  mixture — Lesson 
XVII.  7,  (^.),  i.e.,  ammonio-sulphate  of  magnesia,  which  gives  a 
precipitate  of  phosphates.  Calcium  phosphate  is  the  most  abundant 
salt.     There  is  a  little  magnesium  phosphate. 

(b.)  Silver  nitrate  gives  a  precipitate  insoluble  in  nitric  acid, 
indicating  chlorides  (chiefly  potassium  and  sodium). 

8.  Boil  milk  in  a  porcelain  capsule  for  a  time  to  cause  evapora- 
tion. It  is  not  coagulated,  but  a  pellicle  forms  on  the  surface. 
Remove  it  and  boil  again ;  another  pellicle  is  formed. 

9.  Coagulation  of  Milk. — Calcium  salts  seem  to  play  an  important  part  in 
this  process. 

(i.)  Halliburton's  Method. — Prepare  pure  caseinogen  by  saturating  milk 
with  powdered  MgSOj.  Allow  it  to  stand  for  a  few  hours  and  filter.  Keep 
the  filtrate  (A).  The  filter  residue  consists  of  caseinogen  +  fat;  wash  this  with 
saturated  solution  of  MgS04  until  the  washings  contain  no  albumin.  On 
adding  water  to  the  precipitate,  it  dissolves,  the  fat  remaining  in  the  filter. 

Precipitate  the  solution  of  caseinogen  in  weak  MgS04  by  acetic  acid.  Collect 
the  precipitate  on  a  filter  and  wash  the  acid  away  with  distilled  water. 
Dissolve  the  precipitate  in  lime  water,  rubbing  it  up  in  a  mortar,  filter  = 
opalescent  solution  of  caseinogen. 

Place  some  of  this  opalescent  solution  of  caseinogen  in  two  tubes  A  and  B. 

To  A  add  rennet  and  keep  at  40""  C.  =  no  coagulation. 

To  B  add  rennet  and  a  few  drops  of  phosphoric  acid  (.5  percent.).  Heat  to 
40°  C.  =  coagulation,  i.e.,  casein  is  formed  from  caseinogen  in  the  presence  of 
calcic  phosphate. 

(ii.)  Ringer's  Method  to  show  the  conversion  of  caseinogen  into  casein. — 
Precipitate  caseinogen  ( -f-  fat)  with  acetic  acid.  Collect  and  wash  the  pre- 
cipitate, and  grind  it  up  in  a  mortar  with  calcium  carbonate.  Throw  the 
mixture  into  excess  of  distilled  water.  The  fat  floats,  the  excess  of  calcium 
carbonate  falls  to  the  bottom,  while  the  very  opalescent  solution  contains  the 
caseinogen.     Divide  the  fluid  into  three  tubes  A,  B,  C.     Koep  all  at  40°  C. 

To  A  add  rennet  =  no  clot  of  casein. 

a 


98  PKACTICAL   PHYSIOLOGY.  [XIII. 

To  B  a  few  drops  of  lo  per  cent,  solution  of  calcium  chloride  — no  clot  of 
casein. 

To  C  rennet  and  calcium  chloride  — clot  of  casein, 

10.  Opacity  of  Milk — Vogel's  Lactoscope. 

Apparatus  required. — A  graduated  cylindrical  cc.  measure  to  hold  200  cc.  ; 
a  lactoscope,  with  parallel  glass  sides,  5  mm.  apart  (fig.  50)  ;  a  burette  finely 
graduated  :  a  stearin  candle. 

Method. — (a.)  Be  certain,   by  microscopical   examination,  that  the  milk 
contains  no  starch,  or  chalk,  or  other  granular  impurity. 
{b.)  Mix  3  cc.  of  milk  with  100  cc.  of  water  in  the 
cylindrical  measuring  glass. 

(c.)  In  a  dark  room  place  the  lactoscope  on  a  table, 
and  I  metre  distant  from  it  a  lighted  stearin  candle. 
Fill  the  lactoscope  with  the  diluted  milk,  and  look  at 
the  candle  flame  through  the  glass.  If  the  contour  of 
-Lactoscope.  the  flame  can  be  seen  distinctly,  pour  back  the  diluted 
milk  into  the  bottle,  and  add  another  cc.  of  milk.  Mix 
again.  Test  the  mixture  again,  and  repeat  until,  on  looking  through  the 
glass,  the  outline  of  the  candle-flame  can  no  longer  be  recognised.  Add 
together  the  quantities  of  milk  used.  An  empirical  table  constructed  by 
Vogel  gives  the  percentage  of  fat. 

11.  Wheaten  Flour. — According  to  Martin,  gluten  as  such  does 
not  exist  in  flour.  It  appears  that  the  two  proteids  which  it  con- 
tains— vegetable  myosin  and  an  albumose — when  mixed  with  water 
undergo  certain  changes,  and  become  converted  into  the  insoluble 
proteid  gluten. 

(a.)  Gluten. — Moisten  some  flour  with  water  until  it  forms  a 
bough  tenacious  dough ;  tie  it  in  a  piece  of  muslin,  and  knead  it  in 
a  vessel  containing  water  until  all  the  starch  is  separated.  There 
remains  on  the  muslin  a  greyish- white,  sticky,  elastic  mass  of 
"crude  gluten,"  consisting  of  the  insoluble  albumenoids,  some  of 
the  ash,  and  the  fats.  Draw  out  some  of  the  gluten  into  threads, 
and  observe  its  tenacious  characters. 

(b.)  Dry  some  of  the  gluten,  and  heat  it  strongly  in  a  test-tube  ; 
an  ammoniacal  odour  similar  to  that  of  burned  feathers  is  evolved. 
Water,  which  is  alkaline  (due  to  ammonia),  condenses  in  the  upper 
part  of  the  tube. 

(c.)  Extract  10  grams  of  wheaten  flour  with  50  cc.  of  water  in 
a  large  flask.  Shake  it  from  time  to  time,  and  allow  it  to  stand 
for  several  hours.  Filter.  If  the  filtrate  is  not  quite  clear,  filter 
again.  Heat  a  part  of  the  clear  filtrate,  and  observe  the  coagula- 
tion of  vegetable  albumin. 

(d.)  Test  another  portion  of  the  filtrate  from  (c.)  for  the  xantho- 
proteic reaction. 

(e.)  Another  portion  of  (c.)  is  to  be  precipitated  by  acetic  acid 
and  ferro-cyanide  of  potassium. 

(/.)  Test  a  third  portion  of  (c.)  for  the  reaction  with  NaHO  and 


XIV.]  MUSCLE.  99 

CuSO^.  This  is  best  seen  on  slightly  heating.  Take  care  not  to 
boil  the  liquid,  or  the  reaction  for  sugar  will  be  got  instead. 

{g.)  Extract  some  wheaten  flour  with  a  lo  per  cent,  solution  of 
common  salt  for  twelve  hours.  Filter,  and  drop  some  of  the  clear 
filtrate  into  a  large  vessel  of  water ;  a  milky  precipitate  of  a 
globulin  is  obtained. 

(h.)  On  saturating  some  of  the  filtered  saline  extract  {g,)  with 
powdered  NaCl  or  MgSO^,  a  precipitate  of  a  globulin  is  thrown 
down. 

(t.)  Fats. — Shake  lip  some  wheaten  flour  with  ether  in  a  cylindrical  stop- 
])ered  vessel  or  test-tube,  with  a  tight  fitting  cork.     Allow  the  mixture  to 
stand  for  an  hour,  shaking  it  from  time  to  time.      Filter  off  the  ether  ;  place 
some  of  it  on  a  perfectly  clean  watch-glass,  and  allow  it  to  evaporate  spon 
taneously,  when  a  greasy  stain  will  be  left. 

{j.)  The  chief  salt  is  potassium  phosphate.  The  watery  extract 
gives  a  yellow  precipitate  with  platinic  chloride,  showing  the 
presence  of  potassium ;  while  heating  it  with  molybdate  of  am- 
monium and  nitric  acid  gives  a  canary-yellow  precipitate,  proving 
the  presence  of  phosphates. 

12.  Pea-Meal. 

(a.)  Make  corresponding  watery  and  saline  extracts,  and  perform 
the  same  experiments  with  them  as  in  Lesson  XIII.  11,  (c*.),  (J.), 

(«•)>  (/■),  (?•).  (h.). 

(b.)  Observe  the  copious  precipitate  on  boiling  the  watery  extract. 

(c.)  Note  specially  the  copious  deposit  of  globulin  on  adding  the 
saline  extract  to  water. 

13.  Bread. 

(a.)  Make  a  watery  extract  with  warm  water,  filter,  and  test  the 
filtrate.     Its  reaction  is  alkahne. 

(b.)  Test  for  starch  and  sugar. 

(c.)  The  insoluble  residue  gives  the  xanthoproteic  and  other 
proteid  reactions. 


LESSON  XIV. 
MUSCLE. 


1.  Reaction. 

(a.)  Arrange  two  strips  of  glazed  litmus-paper,  one  red  and  one 
blue,  side  by  side.  Pith  a  frog  ;  cut  out  the  gastrocnemius,  remove 
as  much  blood  as  possible,  divide  the  muscle  transversely,  and 
press  the  cut  ends  on  the  litmus-paper ;  a  faint  blue  patch  is  pro- 


lOO  PRACTICAL   PHYSIOLOGY.  [XIV. 

duced  on  the  red  paper,  showing  that  the  muscle  is  alkaliTie  during 
life.     The  blue  paper  is  not  affected. 

{b. )  Test  the  reaction  of  a  piece  of  butcher's  meat ;  it  is  intensely  acid,  due 
to  sarco-lactic  acid. 

(c*. )  Dip  the  other  gastrocnemius  into  water  at  50°  C.  until  rigor  caloris 
sets  in.     Test  its  reaction  ;  now  it  is  acid. 

(rf, )  Boil  some  water,  and  plunge  into  it  any  other  muscle  of  the  same 
frog  ;  it  is  alkaline. 

{c. )  Tetanise  a  muscle  for  a  long  time  ;  its  reaction  becomes  acid. 

2.  Watery  and  Saline  Extracts. 

{a.)  Mince  some  perfectly  fresh  muscles  from  a  rabbit  or  dog. 
Extract  with  water,  stirring  from  time  to  time.  After  half  an 
hour,  pour  off,  and  filter  the  watery  extract.  Re-extract  the 
remainder  with  water  untn  the  extract  gives  no  proteid  reactions. 
For  the  purposes  of  this  exercise,  half  an  hour  is  sufficient.  Keep 
the  filtrate,  which  contains  the  substances  soluble  in  water. 

{b.)  Take  some  perfectly  fresh  muscle  from  a  rabbit,  rub  it  up 
with  sand  in  a  mortar,  and  extract  it  with  a  large  volume  of  13 
p.c.  solution  of  ammonium  chloride,  or  10  p.c.  NaCl,  or  5  p.c. 
MgSO^.  Stir  occasionally,  and  allow  it  to  extract  for  an  hour.  A 
stronger  extract  is  obtained  if  it  be  left  until  next  day.  Pour  off  the 
fluid,  keep  it,  as  it  contains  the  substances  soluble  in  saline  solutions 
— the  globulins. 

3.  With  the  filtrate  of  2  (a.)— 

(a.)  Test  for  proteids,  e.g.,  serum-albumin. 

(6.)  Test  the  coagulating  point  of  the  proteids  it  contains  (45* 
and  75"  C). 

(c.)  Add  crystals  of  ammonium  sulphate  to  saturation,  which 
precipitates  all  the  proteids. 

4.  With  the  filtrate  of  2  (^.)— 

(a.)  Pour  a  few  drops  into  a  large  quantity  of  water;  observe 
the  milky  deposit  of  myosinogen.  The  precipitate  is  redissolved 
by  adding  a  strong  solution  of  common  salt. 

(b.)  Test  the  coagulating  point.  Foiu*  proteids  are  coagulated 
by  heat  at  47°,  56°,  63°,  and  73°  C,  an  albumose  being  left  in 
solution.     The  fluid  is  acid  in  reaction. 

(c.)  Saturate  the  filtrate  with  crystals  of  sodic  chloride  or 
ammonium  chloride.     The  myosinogen  is  precipitated. 

(d.)  Collect  some  of  the  precipitate  of  4  (<-.),  dissolve  it  with  a 
weak  solution  of  common  salt,  and  test  for  proteid  reactions 
(Lesson  I.  1).     Repeat  3  (c). 

(e.)  Suspend  in  the  fluid  a  crystal  of  rock-salt;  the  latter  soon  becomes 
coated  with  a  deposit  of  myosinogen. 


XIV.] 


MUSCLE. 


lOI 


5.    The    Extractives    of   Muscle. — Prepare    Kreatin    (C4HyN302  +  H20) 
omitting  the  others. 

(a.)  Make  a  strong  watery  solution  of  Liebig's  extract  of  moat.  Cautiously 
add  lead  acetate  until  precipitation  ceases,  avoiding  excess  of  the  lead.  Filter, 
pass  sulphuretted  hydrogen  through 
the  filtrate  to  get  rid  of  the  lead. 
A  pellicle  is  very  apt  to  form  on  the 
surface.  Filter,  and  evaporate  the 
filtrate  to  a  syrup  on  a  water-bath, 
and  set  it  aside  in  a  cool  place  to 
crystallise.  Crystals  of  kreatiii 
separate  out. 

(b.)  After  several  days,  when 
the  kreatin  has  separated,  pour 
off  the  mother-liquor,  add  to  it  5 

volumes  of  90  per  cent,  alcohol  to  precipitate  more  kreatin.  Filter,  wash 
the  crystals  with  alcohol,  redissolve  them  in  boiling  water,  allow  them  to 
recrystallise,  and  examine  them  with  the  microscope  (fig.  51). 

Sarkin  and  xanthin  may  be  prepared  from  the  alcoholic  filtrate  of  (/;.). 

The  following  scheme  after  Salkowski  shows  the  process  of  making 
it  from  flesh. 

Preparation  of  Kreatin. 

Minced  flesh,  digested  with  water,  strained. 


FlO.  51.— Crystals  of  Kreatin. 


Filtrate  heated  to 
boiling,  filter. 


Residue. 


Filtrate  +  lead  acetate 
filter. 


Residue  =  coagulated 
albumin. 


Filtrate  +  HgS  to  remove 
lead,  filtrate  concentrated 

=  Kreatin. 


Deposit  =  phosjjhate 

chloride  and  sulphate 

of  lead. 


test. 


6.  Liebig's  Extract  of  Meat. 

{a.)  Test  it  for  proteids ;  they  are  absent. 

{h.)  Test  it  for  glycogen,  doing  a  control 
tains  a  small  quantity. 

(c.)  Test  it  for  kreatinin  (see  "Urine"), 
succeeds. 

{(l.)  Examine  it  microscopically ;  in  addition  to  a  few  crystals 
of  common  salt,  a  few  clear  knife-rest  forms,  there  are  numerous 
crystals  of  kreatin. 


It  usually  con- 
Weyl's  test  usually 


I02 


PRACTICAL   PHYSIOLOaY. 


[XIV. 


ADDITIONAL  EXERCISES. 

7.  Muscle-Plasma. — Kill  a  rabbit  by  bleeding  from  the  carotids,  open  the 
abdomen,  insert  a  cannula  in  the  aorta,  and  wash  out  all  the  blood  from  the 
lower  limbs  by  means  of  a  stream  of  cold  saline  solution  (0.6  ])er  cent., 
NaCl).  The  solution  is  made  cold  enough  by  placing"  lumps  of  ice  in  it. 
Skin  the  limbs  quickly,  cut  oil"  ])ieces  of  the  muscle  and  plunge  them  into  a 
mixture  of  salt  and  ice  (1°  -  2"^  C),  where  they  quickly  become  quite  hard  and 
frozen.  When  they  are  frozen  remove  them  from  the  mixture,  wipe  them 
with  blotting-paper,  and  place  them  on  a  plate  kept  cold  by  ice  and  salt 
mixture.  Cut  them  into  fine  slices  (cutting  parallel  to  the  direction  of  the 
fibres).  Wrap  the  slices  in  linen  and  squeeze  them  in  a  pair  of  cooled  enamelled 
iron  lemon-squeezers  ;  a  yellowish,  viscid  alkaline  plasma  is  obtained,  which 
sets  in  the  course  of  an  hour  or  so  into  a  solid  jelly,  with  the  simultaneous 
appearance  of  an  acid  reaction.  By-and-by  a  clear  clot  of  myosin  and  a  fluid 
muscle-serum  is  obtained,  just  as  in  a  blood-clot.  The  muscle-plasma  con- 
tains several  proteids.  For  fall  details  of  these  see  Halliburton,  Journal  of 
Physiology,  viii.  p.  133. 

8.  Halliburton's  Researches  on  Proteids  of  Muscle. — With  a  stream  of 
normal  saline  solution  wash  out  the  blood-vessels  of  a  rabbit  just  killed.  Do 
this  by  placing  a  cannula  in  the  aorta.  Remove  the  muscles  quickly,  chop 
them  up  and  extract  for  a  day  with  5  per  cent,  solution  of  magnesium  sul- 
phate.    This  is  done  by  the  demonstrator.     Use  this  fluid. 

{a.)  It  is  probably  acid  due  to  lactic  acid.     Test  for  this  (p.  78). 
(ft.)  Coagulation.     Dilute  some  with  4  vols,  of  water,  divide  it  into  two 
parts,  keep  one  at  40°  C.  (rapid  coagulation)  and  the  other  at  the  ordinary 
temperature  (coagulation,  but  slower).     Clot  of  myosin  formed  in  both. 

(c.)  Remove  the  clotted  myosin  from  (ft.)  ;  it  is  readily  soluble  in  0.2  per 
cent.  HCl,  forming  syntonin  ;  and  also  in  10  per  cent,  sodium  chloride. 

{d.)  Add  a  few  drops  of  2  per  cent,  acetic  acid  to  some  of  the  extract  = 
stringy  precipitate  of  myosinogen. 

(«.)  Perform  fractional  heat  coagulation  {Halliburton)^  p.  11. 

**  (i.)  With  the  original  extract  coagula  are  obtained  at  47°,  56°,  63°,  73°  C. 
"  (ii.)  With  liquid  (salted  muscle-serum)  from  <h.),  after  separation  of  the 

clot,  coagula  are  obtained  at  63°  and  73°  C. 
*'(iii.)  With  muscle-extract  which  has  been  saturated  with  MgSOj  and 
filtered.     The  globulins  are  thus  separated.     Coagulation  now  occurs 
at  Ti"  C,  but  the  coagulum  is  small." 
The  following  table  from  Halliburton  shows  these  facts : — 


N«™o">ro«id.;^e™TSu,°. 

Action  Of  M«SO.YoViCnrin" 

Fate. 

Myosinogen 
Myosinogen. 
Myo-globulin. 
Myo-albuniin. 

47°  C. 
56- C. 
63*0. 
73- C. 

Precipitated. 
Not  precipitated. 

Globulin. 
Albumin. 

)^  These  form   muscle-clot 
)       or  Myosin. 
\  These  are  left  In  mvscU- 
f      serum. 

9.  Pigments  of  Muscle. 

{a.)  Notice  the  diff'erence  between  the  red  (semi-tendinosus)  and  pale  muscles 
(adductor  magnus)  of  the  rabbit. 

(ft.)  The  muscular  part  of  the  diaphragm  shows  the  spectrum  of  oxy-hflemo- 
globin,  even  after  the  blood-vessels  have  been  washed  out  by  salt  solution 
(Kuhne). 


XV.]  SOME   IMPORTANT  ORGANIC   SUBSTANCES.  IO3 

(c.)  A  piece  of  the  great  pectoral  muscle  of  a  pigeon,  either  fresh  or  which 
has  been  placed  in  glycerine  to  render  it  more  transparent,  on  being  pressed 
between  two  pieces  of  glass  shows  absorption  bands  of  myo-hsematin,  {Mac- 
Munn.)    Map  out  their  position  with  the  spectroscope. 


LESSON  XV. 
SOME   IMPORTANT   ORGANIC   SUBSTANCES. 

1.  Hydrochloride  of  Glycosamin. — The  chitinous  parts  of  crabs  and  lob- 
sters are  freed  as  much  as  possible  from  their  soft  parts,  dried,  and  divided 
into  small  pieces,  which  are  decalcified  in  dilute  hydrochloric  acid.  Gently 
boil  the  decalcified  parts  for  3-4  hours  with  hydrochloric  acid,  then  evaporate 
and  allow  to  crystallise.  On  cooling,  a  dark  brown  humus  substance  and 
crystals  separate  out.  Filter,  dissolve  the  crystals  in  water,  and  re-evap- 
orate until  crystallisation  takes  place.  The  hydrochloride  of  glycosamin 
(CgHigNOaHCl)  separates  in  colourless  glancing  crystals  about  the  size  of  a 
pea,  which  readily  reduce  Fehling's  solution  on  boiling.  They  have  a  some- 
what sweet  taste  like  sugar, 

2.  Nuclein  of  Yeast. — Mix  i  part  of  fresh  German  yeast  with  4  parts  o*' 
water,  allow  the  deposit  to  subside.  Pour  off  the  turbid  fluid  from  the  pI;,  - 
deposit  of  yeast,  place  the  latter  in  .5  per  cent,  caustic  potash,  stir  for  some 
time,  and  filter  directly  into  dilute  hydrochloric  acid.  The  deposit  is  filtered 
off,  washed  with  dilute  hydrochloric  acid,  and  then  with  alcohol.  It  is  then 
boiled  with  alcohol  and  dried  over  sulphuric  acid. 

(a.)  It  is  an  amorphous  powder,  insoluble  in  water  and  dilute  acids,  but 
readily  soluble  in  alkalies. 

{b.)  Fuse  a  little  with  sodic  carbonate  and  nitrate  of  potash  =» a  mass  with 
a  strongly  acid  reaction  due  to  phosphoric  acid. 


8.  Lecithin. 


ro.Ri 
,hJ  O.R 
to.po 


^^^  O.CH..CH 


(CH3)g 


JN.OH. 


Extract  the  fresh  yellow  of  eggs  free  fromf  white,  with  ether,  until  the  latter 
takes  up  no  more.  Distil  off  the  ether,  dissolve  the  residue  in  petroleum 
ether,  and  filter.  Extract  the  filtrate  in  a  separation  filter  several  times  with 
75  per  cent,  alcohol.  Mix  the  alcohol  extracts,  let  them  stand  until  they 
become  clear,  separate  any  j)etroleum  ether,  and  filter.  The  rest  of  the  petro- 
leum ether  is  got  rid  of  by  distillation,  and  the  residue  is  exposed  for  several 
days  to  the  air  in  a  cool  place,  whereby  a  deposit  separates.  The  clear  fluid 
is  decanted  and  filtered.  Decolorise  it  by  boiling  with  animal  charcoal,  filter 
and  evaporate  to  a  thick  syrup  at  50-60".  Dissolve  the  syrup  in  ether  and 
evaporate,  and  the  nearly  pure  lecithin  remains  behind  {Drcdisel). 

^  R=  radical  of  palmitic  acid  (C15H31CO),  stearic  acid  (C17H35CO),  or  oleic 
acid  (C17H33CO). 


104  PRACTICAL  PHYSIOLOGY.  [XVL 

(a.)  It  is  a  soft  doughy  indistinctly  crystalline  body.  Place  a  little  under 
a  microscope,  add  a  drop  of  water,  and  observe  the  oil-like  drops  assuminj 
worm-like  forms,  so-called  "myelin-fornis." 

{b.)  Heat  some  on  platinum,  either  alone  or  with  sodic  carbonate  and 
potassic  nitrate  =  a  residue,  strongly  acid,  in  which  phosphoric  acid  is  readily 
detected. 

(c.)  Action  on  Polarised  Light. — Examine  a  little  under  a  polarisation 
microscope.  With  crossed  Nicol's  each  granule  of  the  substance  shows  a 
dark  cross  on  a  white  ground,  just  like  starch  {Dastre). 

4.  GlycocoU.— C  |  ^|^   CO. OH  \  _  c.^HjNOo  or  amido-acetic  acid. 

Preparation. — Boil  i  part  of  hippuric  acid  with  4  parts  of  dilute  sulphuric 
acid  (i  :  6  water)  for  ten  to  twelve  hours  in  connection  with  a  condenser. 
Carefully  pour  the  mass  into  a  capsule  and  let  it  stand  for  twenty-four  hours. 
Filter,  wash  the  benzoic  acid  in  the  filter  with  cold  water,  concentrate  the 
filtrate  by  evaporation,  and  free  it  from  the  last  traces  of  benzoic  acid  by 
shaking  it  with  ether.  Dilute  strongly  the  acid  solution,  and  neutralise  it 
exactly  with  baryta  water.  Allow  the  precipitate  to  subside,  decant,  wash 
the  precipitate  with  warm  water,  again  concentrate  the  filtrate  until  crystals 
begin  to  separate  on  its  surface.  Allow  it  to  stand  twenty-four  hours,  pour 
off  the  mother-liquid,  and  again  evaporate  the  latter  until  other  crystals  are 
formed.     The  crystals  are  recrystallised  from  water. 

GlycocoU  forms  clear  colourless  crystals,  with  a  sweet  taste,  readily  soluble 
in  water,  and  insoluble  in  alcohol. 

5.  Guanin  Reaction. — Guanin  occurs  in  very  considerable  quantity  in  the 
skin  of  fishes  and  frogs.  Heat  a  small  piece  of  the  skin  fi'om  the  belly  of  a 
frog,  and  heat  it  on  a  porcelain  capsule  with  HNO^  as  for  the  murexide  test 
(p.  128).  Add  caustic  soda  =  orange  to  cherry-red  colour.  There  is  no  re- 
action with  ammonia.  If  there  be  very  little  guanin,  add  dilute  caustic 
potash,  and  blow  on  the  stain  to  cool  it,  when  the  latter  will  pass  through 
several  nuances  from  blue  to  orange. 

6.  Nucleo- Albumin,  called  "  tissue-fibrinogen  "  by  Wooldridge,  is  best  pre- 
pared by  Halliburton's  method. 

Sodium  Chloride  Method, — The  finely  divided  thymus  gland  is  ground  up 
in  a  mortar  with  an  equal  volume  of  sodium  chloride.  The  viscous  mass,  on 
being  poured  into  excess  of  distilled  water,  forms  stringy  masses  which  rise  to 
the  surface.  Collect  and  dissolve  these  in  i  per  cent,  sodium  carbonate 
solution.  A  few  cc.  of  a  clear  filtered  solution  injected  into  the  blood-vessels 
of  a  rabbit  produce  extensive  intra  -  vascular  clotting,  especially  in  the 
veins. 


LESSON  XVI. 
THE     URINE. 


1.  Urine  is  a  transparent  liglit-straw  or  amber-coloured  watery 
secretion  derived  from  the  kidneys,  containing  nitrogenous  or 
azotised  matters,  salts,  and  gases.  The  most  abundant  constituents 
are  water,  urea,  and  sodium  chloride.  It  has  a  peculiar  odour,  bitter 
saltish  taste,  and  acid  reaction. 


XVI.] 


THE   URINE. 


105 


2.  Quantity. — Normal. — About  2 J  pints  (50  ounces)  or  150c 
cc.  in  twenty-four  hours,  although  there  may  be  a  considerable 
variation  even  in  health,  the  quantity  being  regulated  by  the 
amount  of  fluid  taken,  and  controlled  by  the  state  of  the  tissues, 
the  pulmonary  and  cutaneous  excretions. 

Collection. — It   should   be   collected   in   a  tall  graduated  glass 
cylinder  of   a  capacity   of    2500   cc.   with  a  ground  glass  top  to 
exclude   impurities.      Samples  of   the  mixed  urine  of 
the  24  hours  are  used  for  examination. 


.._  lOOft 
101D 

.._  10«0 
._1080 
_1040 


Increastd  by  drinking  water  {u.rina  potns)  or  diuretics  ;  when 
the  skin  is  cool,  its  blood-vessels  are  contracted,  and  the  cutaneous 
secretion  is  less  active  ;  after  a  paroxysm  of  hysteria,  and  some 
convulsive  nervous  diseases  ;  in  diabetes  imipidus  and  d.  inellUus; 
some  cases  of  hypertrophy  ot  the  left  ventricle,  and  some  kidney 
diseases.  The  increase  may  be  temporary  or  persistent,  the 
former  as  the  effect  of  cold,  diuretics,  or  nervous  excitement ; 
the  latter  in  diabetes  and  certain  forms  of  kidney-disease. 

Diminished  after  profuse  sweating,  diarrhoea  ;  early  stage  of 
acute  Bright's  disease ;  some  forms  of  Bright's  disease ,  the 
last  stages  of  all  forms  of  Bright's  disease  ;  in  general  dropsies  ; 
in  acute  febrile  and  inflammatory  diseases. 

3.  Colour. — Normal. — Light-straw  to  amber-coloured,  ^--g^ 
The  colour  varies  greatly  even  in  health,  and  is  due  'i!!i  «( 
to  the  presence  of   a   mixture  of    pigments,    probably  I      ■! 
largely  derived  from  the  decomposition  of  haemoglobin,  j   ;: 
Of  these  pigments  urobilin,  an  iron-free  derivative  of  *  "' 
Hb,  is  the  chief.     The  colour  largely  depends  on  the 
degree  of  dilution  of  the  urine  pigments. 

Pale  after  copious  drinking,  in  diabetes,  anaemia,  and  chlorosis; 
after  paroxysmal  nervous  attacks  (hysteria).  N.B.  —Pale  urines 
indicate  the  absence  of  fever. 

High-coloured  after  severe  sweating,  violent  muscular  exercise, 
diarrhoea,  or  during  febrile  conditions. 

Pathological  pigments,  purpurine  or  uro-erythrine  in  febrile 
disorders  ;  bile  pigments  ;  blood. > 

Medicinal  Siolistances. — Creosote  and  carbolic  acid  make  urine 
nearly  black.  This  is  due  not  to  carbolic  acid,  but  to  hydro- 
chinon.  Sometimes  these  urines  become  almost  black  on  stand- 
ing exposed  to  the  air.  Rhubarb  (gamboge-yellow) ;  senna 
(brownish). 

Fio.  52. 

4.  Specific    Gravity.  —  Normal^   s.g.    1020    (1015-    urinometer. 
1025). — This  is   taken  by  means  of   the   urinometer 

(fig.  52).  The  instrument  ought  to  be  tested  by  placing  it  in  a 
cylindrical  vessel  filled  with  distilled  water  to  ascertain  that  its 
zero  is  correct. 

(a.)  Fill   a   tall   cylindrical   vessel    with   urine,    and   place   the 


I06  PRACTICAL  PHYSIOLOGY.  [XVL 

urinometer  in  it.  Bring  the  vessel  to  the  level  of  the  eye,  and  as 
soon  as  the  instrument  comes  to  rest,  read  off  the  mark  on  its 
stem  opposite  the  lower  surface  of  the  meniscus  against  a  bright 
back-ground. 

Precautions. — i.  The  vessel  must  be  so  wide  that  the  urinometer  can  float 
freely  and  not  touch  the  sides.  2.  The  instrument  must  be  dry  before  being 
placed  in  the  fluid.  3.  The  urine  itself  must  be  clear  and  free  from  air- 
Ijubbles  on  the  surface  ;  the  latter  can  be  readily  removed  by  means  of  a  fold 
of  blotting-paper.  N.B.  —  It  is  always  necessary  to  take  the  specific  gravity 
of  the  "mixed"  urine  of  twenty -four  hours. 

Low  S.G. — Under  normal  conditions  the  s.g.  varies  inversely  as  the  quantity 
of  urine  passed.  All  causes  which  increase  the  water  of  the  urine  only,  e.g., 
drinking  on  an  empty  stomach  ;  after  hysteria  ;  in  diabetes  inslpidiis  ox  poly- 
dipsia. N.  B.  — If  continually  below  loi  5,  suspect  diabetes  insipidus  or  chronic 
Bright's  disease. 

Nigh  S.G. — "When  the  urine  is  concentrated,  diabetes  mellitus,  due  to  a 
large  amount  of  grape  sugar  ;  first  stages  of  acute  fevers  ;  rapid  wasting  of 
the  tissues,  especially  if  associated  with  sweating  or  diarrhoea.  It  is  highest 
normally  three  to  four  hours  after  a  meal ;  and  as  it  varies  during  the  day,  it 
is  necessary  to  mix  the  urine  of  the  twenty- four  hours,  and  test  the  specific 
gravity  of  a  sample  of  the  "mixed  urine."  N.B. — If  above  1025  and  the 
urine  be  pale,  suspect  saccharine  diabetes. 

5.  Estimation  of  the  Amount  of  Solids  from  the  S.G, — By 

Cliristison's  formula  {''  Hdscr-l'rapp's  coefficient''')^  "multiply  the 
last  two  figures  of  a  specific  gravity  expressed  in  four  figures  by 
2.33.  This  gives  the  quantity  of  soKd  matter  in  every  1000  parts," 
i.e. J  the  number  of  grams  in  1000  cc.  (3  3  J-  oz.). 

Example. — Suppose  a  patient  to  pass  1200  cc.  of  urine  in  twenty  four  hours, 
and  the  sp.  gr.  to  be  1022,  then 

22  X  2.33  =  51.26  grams  in  1000  cc 

To  ascertain  the  amount  in  1200  cc. 

51.26x1200    , 
1000:  1200:  :  51.26  :a;= j^^ =  61.51  grams. 

This  formula  is  purely  empirical,  and  is  not  a*pplicable  where  the  variations 
are  very  marked,  as  in  saccharine  diabetes  and  some  cases  of  Bright's  disease, 
where  there  is  a  great  diminution  of  urea. 

The  normal  quantity  of  solids,  or  the  total  solids  -  sometimes 
spoken  of  as  "solid  urine" — is  about  70  grams  (2  oz.)  in  twenty- 
four  hours,  i.e.,  1000  to  1050  grains.  Parkes  gives  an  average 
of  945  grains  per  day  for  an  average  adult  male  between  twenty 
and  forty  years  of  age.  The  latter  estimate  gives  about  20  grains 
of  solids  per  fluid  ounce  of  urine,  or  about  4  per  cent,  of  sohds. 

6.  Odom*  is  "  pecuhar  "  and  "  characteristic,"  somewhat  aromatic 
in  health. 


XVI.]  THE  URINE.  IO7 

Certain  medicinal  and  other  substances  influence  it — turpentine  (violets) ; 
cubebs,  copaiba,  and  sandal -wood  oil  give  a  characteristic  odour,  and  so  do 
asparagus,  valerian,  assafoetida,  garlic,  &c.  In  disease^  note  the  annnoniacal 
odour  of  putrid  urine  and  the  so  called  "sweet"  odour  in  saccharine 
diabetes. 

7.  Reaction. — Normal. — Slightly  acid,  it  turns  blue  litmus- 
paper  slightly  red,  and  does  not  affect  red  litmus-paper.  'J'lie 
acidity  is  chiefly  due  to  acid  sodium  phosphate  (jN"aH2P04),  acid 
urates,  and  very  slightly  to  free  acids — lactic,  acetic,  oxalic,  &c. 
A  neutral  urine  does  not  alter  either  blue  or  red  litmus-paper.  A 
ve7y  acid  urine  turns  blue  litmus-paper  very  red. 

(a.)  Test  with  appropriate  litmus-paper  a  normal,  very  acid, 
neutral,  and  alkaline  urine. 

(b.)  Test  also  with  violet  litmus-paper. 

(c.)  That  the  acidity  is  not  due  to  a  free  acid  is  shown  by  its 
giving  no  precipitate  with  sodium  hyposulphite,  and  also  by  the 
fact  that  it  has  no  action  on  congo-red.  The  colour  of  the  latter 
body  is  violet  or  inky,  with  a  solution  containing  i  part  of  free 
hippuric  acid  in  50,000  of  distilled  water. 

8.  Variations  in  Acidity  during  the  Day. — During  digesUon,  i.e., 
two  or  three  hours  after  a  meal,  the  urine  becomes  neutral  or  alka- 
line. The  cause  of  the  alkalinity,  is  a  fixed  alkali,  probably  derived 
from  the  basic  alkaline  phosphates  taken  with  the  food  {Roherls), 
the  ^^alkaline-tide."  According  to  others,  the  formation  of  free 
acid  in  the  stomach  liberates  a  corresponding  amount  of  bases  in 
the  blood,  which  pass  into  the  urine,  and  diminish  its  acidity  or 
even  render  it  alkaline.     The  "  acid-tide  "  occurs  after  fasting. 

Nature  of  the  Food. — With  a  vegetable  diet  the  excess  of  alkali  causes  an 
alkaline  urine.  In  herbivora  it  is  alkaline,  in  carnivora  very  acid.  Herbivora 
(rabbits)  whilst  fasting  have  a  clear  acid  urine,  because  they  are  practically 
living  on  their  own  tissues.  Perhaps  this  is  one  of  the  reasons  why  the  urine 
is  so  acid  in  fevers.  Inanition  renders  the  urine  renj  acid  {Chossal).  In 
herbivorous  animals  and  vegetarians,  the  excess  of  alkaline  salts  of  citric, 
tartaric,  and  other  acids  being  oxidised  into  carbonates  render  it  alkaline. 

Medicines. — Acids  slightly  increase  the  acidity.  Alkalies  and  their  car- 
bonates are  more  powerful  than  acids,  and  soon  cause  alkalinity  ;  alkalies, 
e.g.^  the  alkaline  salts  of  citric,  tartaric,  malic,  acetic,  and  lactic  acids,  appear 
as  carbonates  ( Wohler). 

9.  Alkalinity  may  be  due  to  the  Presence  of  a  Fixed  or  a 
Volatile  Alkali. — In  the  former  case,  the  blue  colour  of  the  litmus- 
paper  does  not  disappear  on  heating ;  in  the  latter  it  does,  and  the 
paper  assumes  its  original  red  colour. 

{a.)  Test  with  two  pieces  of  red  litmus-paper  two  samples  of 
urine,  one  alkahne  from  a  fixed  alkali,  and  the  other  from  a  vola- 
tile one.     Both  papers  become  blue. 


I08  PRACTICAL  PHYSIOLOGY.  [XVI 

(b.)  Place  both  side  by  side  on  a  glass  slide,  heat  them  carefully, 
and  note  that  the  blue  colour  of  the  one  disappears  (volatile  alkali), 
the  red  being  restored,  while  the  blue  of  the  other  remains  (fixed 
alkali). 

The  alkalinity  may  be  caused  by  the  presence  of  ammonium  carbonate 
(volatile),  derived  from  the  decomposition  of  urea  ;  the  urine  may  be  ammonia- 
cal  when  passed,  in  which  case  there  is  always  disease  of  the  urinary  mucous 
membrane  ;  or  it  may  become  so  on  standing— from  putrefaction — when  it  is 
always  turbid,  and  contains  a  sediment  consisting  of  amorphous  phosphate  of 
lime  and  triple-phosphate,  and  sometimes  urate  of  ammonium  ;  it  has  an 
otlensive  ammoniacal  odour,  and  is  very  irritating  to  the  mucous  membrane. 

The  acidity  is  increased  during  the  resolution  of  febrile  diseases  ;  is  excessive 
in  gout  and  acute  rheumatism,  and  whenever  much  uric  acid  is  given  off  (uric 
acid  diathesis) ;  in  saccharine  diabetes  ;  when  certain  acids  are  taken  with  the 
food  (COo,  benzoic). 

The  amount  of  the  acidity  may  be  determined  by  using  a  standard  solution 
of  caustic  soda  (p.  i  lo). 


f-— * 


YiQ.  53.— Deposit  in  "  Acid  Fermentation  "  of  Urine,    a.  Fungus ;  6.  Amorphous 
sodium  urate  ;  c.  Uric  acid  ;  d.  Calcium  oxalate. 

10.  Transparency. — Observe  whether  the  urine'  is  quite  trans- 
parent or  contains  any  suspended  particles,  rendering  it  more  or 
less  turbid,  either  when  it  is  passed,  or  some  time  afterwards. 

11.  Fermentation  of  Urine. — When  urine  is  freely  exposed  to 
the  air  it  undergoes  two  fermentations — (i)  the  acid;  (2)  the 
alkalme.  The  urine  at  first  becomes  slightly  inore  acid,  from  the 
formation  of  lactic  and  acetic  acids  (although  this  is  denied  by  some 
observers),  then  it  gradually  becomes  neutral,  and  finally  alkaline 
from  putrefaction.  It  becomes  lighter  in  colour,  turbid,  and  a 
whitish  heavy  precipitate  occurs ;  a  pellicle  forms  on  the  surface,  it 


XVI.] 


THE   URINE. 


109 


swarms  with  bacteria,  and  it  has  an  ammoniacal  odour,  which  is 
due  to  the  splitting  up  of  the  urea,  thus — 

CON2H4  +  2H2O  =  (NH4),C03. 

The  urea  is  split  up  by  a  ferment  formed  by  the  micrococcus 
urex.  The  carbonate  of  ammonium  makes  the  urine  alkaline,  and 
the  earthy  phosphates  are  precipitated  because  they  are  insoluble  in 
an  alkaline  urine.  The  phosphate  of  lime  is  precipitated  as  such 
(amorphous),  while  the  phosphate  of  magnesia  unites  with  the 
ammonia  and  is  precipitated  as  ammonio-magnesic  phosphate  or 
triple  phosphate  (MgNH^PO^  +  6H2O).  Part  of  the  ammonia 
escapes,  and  in  addition  to  that  united  to  the  magnesic  phosphate, 
some  unites  with  uric  acid  to  form  urate  of  ammonium. 


ElO.  54.— Deposit  in  Ammoniacal  Urine  (Alkaline  Fermentation),    a.  Ammonlo- 
magnesium  phosphate  ;  d.  Acid  ammonium  urate  ;  c.  Bacterium  urese. 

N.B. — Although  urine  may  be  kept  "  sweet "  for  a  long  time  in 
perfectly  clean  vessels,  still  when  mixed  with  decomposing  matter 
it  rapidly  putrefies.  Insist  that  all  urinary  vessels  be  scrupulously 
clean;  and  that  all  instruments  introduced  into  the  bladder  be 
properly  purified  by  carbolic  acid  or  other  antiseptic. 

(a.)  Place  some  normal  urine  aside  for  some  days,  in  a  warm 
place.  Observe  it  from  day  to  day,  noting  its  reaction,  change  of 
colour,  transparency,  odour,  and  any  deposits  that  may  form  in  it. 
Examine  the  deposit  microscopically  (figs.  53,  54). 

Fermentation  is  liasteyied  by  a  high  temperature,  and  especially 
if  the  urine  be  passed  into  a  contaminated  vessel,  or  the  urine 
itself  contain  blood,  much  mucus  or  pus.  It  is  retarded  in  a  very 
acid  and  concentrated  urine. 


no  PRACTICAL  PHYSIOLOGY.  [XVII. 


ADDITIONAL  EXERCISE. 

12.  Estimation  of  the  Acidity. —This  is  done  by  ascertaining  the  amount 
of  caustic  soda  required  to  exactly  neutralise  lOO  cc.  of  urine.  As  the  soda 
solution  cannot  be  prepared  by  weighing  the  soda  because  of  the  varying 
amount  of  water  contained  in  it,  the  soda  solution  must  be  titrated  with  a 
standard  solution  of  oxalic  acid.  Make  a  nortnal  solution  of  oxalic  acid  by 
dissolving  63  grams  of  dry  crystallised  oxalic  acid  in  1000  cc.  water,  CoHoOj 
+  2H0O  =  126  [i.e. ,  half  the  quantity  is  taken  because  the  acid  is  dibasic").  A 
normal  solution  of  caustic  soda  would  contain  40  grams  per  litre  (NaHO),  i.e., 
N'a  =  23,  H=i,  O=i6)  =  4o).  i  cc.  =40  milligrams  or  .04  gram.  Dissolve 
150  grams  of  caustic  soda  in  about  1000  cc,  water. 

(a.)  Preparation  of  Normal  Caustic  Soda. — Place  10  cc.  of  normal  oxalic 
acid  solution  in  a  beaker,  add  a  few  drops  of  alcoholic  solution  of  rosolic 
acid  (orange  solution),  and  allow  the  caustic  soda  solution  to  drop  from  a 
burette  until  the  rosolic  acid  gives  a  rosy-red  tint.  Suppose  that  to  saturate 
the  acid  9.2  cc.  of  the  soda  solution  are  added,  then  to  every  9.2  cc.  0.8  cc. 
must  be  added  to  obtain  a  solution  of  which  i  cc.  will  correspond  to  i  cc.  of 

acid,  so  that  for  1000  cc.  of  caustic  soda  9.2  :  1000  : :  0.8  :  a;  ( '-  =  86. 9  ) 

86.9  cc.  water  must  be  added. 

(6.)  Determine  the  Acidity  of  Urine. — Place  100  cc.  of  urine  in  a  beaker, 

and  add  to  it  from  a  burette  the  normal  soda  solution  (i  cc.  =0.063  oxalic  acid). 

It  is  better,  however,  to  dilute  the  soda  solution  to  obtain  a  deci-nonnal  solu- 

N 
tion  —  i.e.,  one  tenth  as  strong).     In  this  case,   i  cc.  =.0063  oxalic  acid. 

Place  strips  of  red  litmus-paper  in  the  fluid,  drop  in  the  caustic  soda,  stir,  and 
add  caustic  soda  until  the  litmus  begins  to  turn  blue.     Suppose  15  cc.  of 

the  dilute  (  -  )   solution  are  used,    then  the  acidity  of    100  cc.    urine  = 

15x0.0063  =  0.0945;  and  suppose  the  total  quantity  of  urine  passed  to  be 
1500  CO.,  then  the  total  acidity  of  the  urine  passed  m  twenty- four  hours  ex- 
pressed as  oxalic  acid=  1.417  grams.     The  result  is  merely  approximative. 


LESSON  xvn. 

THE  INORGANIC  CONSTITUENTS  OP  URINE. 

The  constituents  of  the  urine  may  be  classified  as  follows : — 

(i.)  Water  and  inorganic  salts. 

(2.)   Urea  and  relative  nitrogenous  bodies;  uric  acid,   xanthin, 
guanin,  kreatinin,  allantoin,  oxaluric  acid. 

(3.)  Aromatic  substances;  ether-sulpho- acids  of  phenol,   cresol, 
pyrocatechin,  hippuric  acid,  &c. 

(4.)   Fatty  nnn-nitrogenous  bodies;  oxalic,  lactic,  and  glycerin- 
phosphoric  acid. 
i5.)  Pigments, 
6.)  Gases, 


XVII.]          THE   INOllOANIC   CONSTITUENTS   OF    URINE.  Ill 

The  ratio  of  inorganic  to  organic  constituents  is  i  to  1.2 -1.7. 
The  amount  of  salts  excreted  in  twenty-four  hours  is  16  to  24  grama 
(i  to  f  oz.). 

1.  Water  is  derived  from  the  food  and  drink,  a  small  quantity 
being  formed  in  the  body  (normal  quantity  1500  cc,  or  about 
50  oz.). 

2.  Chlorides  are  chiefly  those  of  sodium  (by  far  the  most 
abundant)  with  a  little  potassium  and  ammonium,  derived  chiefly 
from  the  food,  and  amount  to  10  to  13  grams  (150  to  195  grains), 
or  a  mean  of  12  grams  (180  grains).  Sodic  chloride  crystallises 
usually  in  cubes  and  octahedra.  It  sometimes  forms  a  combina- 
tion with  urea,  and  then  it  crystallises  in  rhombic  plates. 

(a.)  Test  with  a  few  drops  of  AgNOs  (i  pt.  to  8  distilled  water) 
=  white,  cheesy,  or  curdy  precipitate  in  lumps  insoluble  in  IINO3. 
The  phosphate  of  silver  is  also  thrown  down,  but  it  is  soluble  in 
HNO3. 

Estimation. — A  rough  estimate  may  be  formed  of  the  amount 
by  allowing  the  precipitate  to  subside,  and  comparing  its  bulk 
from  day  to  day. 

Variations,  increased  in  amount  when  the  urine  is  secreted  in  excess, 
although  the  NaCl  usually  remains  very  constant  (|  per  cent.) ;  lessened  in 
febrile  affections,  and  where  a  large  amount  of  exudation  has  taken  place,  as 
in  acute  pneumonia,  when  chlorides  may  be  absent  from  the  urine.  The 
reappearance  of  chlorides  in  the  urine  is  a  good  symptom,  and  indicates  an 
improvement  in  the  condition  of  the  lung.  iV.^.— The  urine  ought  to  be 
tested  daily  for  chlorides  in  cases  of  pneumonia. 

(b.)  Evaporate  a  few  drops  of  urine  on  a  slide  =  octahedral  or 
rhombic  crystals,  a  compound  of  NaCl  and  urea. 

(c.)  Test  urine  from  a  case  of  pneumonia,  and  compare  the 
amount  of  the  precipitate  with  that  of  a  normal  urine. 

3.  Quantitative  Estimation  of  Chlorides. — {i.)  Standard  Silver  Nitrate. — 
Dissolve  29.075  grams  fused  silver  nitrate  in  1000  cc.  distilled  water,  i  cc. 
-=0.0 1  NaCl. 

(2.)  Saturated  Solution  of  Neutral  Potassic  Chromate. 

(a.)  Dilute  10  cc.  of  not  too  dark-coloured  urine  with  100  cc.  water,  and 
place  it  in  a  beaker;  add  a  few  drops  of  (2).  Allow  the  silver  solution  to  drop 
m,  stirring  all  the  time  until  a  faint  orange  tint  indicates  that  there  is  an  end 
of  the  reaction.  Deduct  i  from  the  number  of  cc.  of  the  silver  solution 
added. 

4.  Sulphates  are  chiefly  those  of  sodium  and  potassium.  The 
total  quantity  of  sulphates  (45  to  60  grs.)  is  3  to  4  grams  daily. 
Only  a  small  amount  of  them  .enters  the  body  with  the  food,  so  that 
they  are  chiefly  formed  from  the  metabolism  of  proteids  in  the 
body.     They  have  no  clinical  significance.     Sulphuric  acid,  how- 


112  PRACTICAL  PHYSIOLOGY.  [XVII. 

ever,  exists  in  urine  not  only  in  combination  with  alkalies,  as 
indicated  above,  so-called  "preformed  sulphuric  acid,"  but  also 
Avith  organic  radicles,  phenol,  skatol,  and  other  aromatic  substances 
forming  aromatic  ether-sulpho-compounds,  or  "  ethereal  sulphates," 
the  "combined  sulphuric  acid."  The  latter  form  about  J^th  of 
the  total  sulphates,  and  originate  from  putrefactive  processes  in  the 
intestine.  The  chief  ethereal  sulphates  are  phenol-sulphate  ot 
potassium  and  indoxyl-sulphate  of  potassium  or  indican  (CgHgN) 
KSO4. 

(a.)  Test  with  a  soluble  salt  of  barium  (the  nitrate  or  chloride) 
=  white  heavy  precipitate  of  barium  sulphate,  insoluble  in  HNO3. 

(/>.)  To  separate  the  combined  (ethereal)  sulphuric  acid, — Mix 
50  cc.  of  urine  with  an  equal  bulk  of  "  baryta  mixture."  Stir  and 
filter.  This  removes  the  ordinary  sulphuric  acid  as  sulphate  of 
barium.  Add  10  cc.  HCl,  and  keep  in  a  water-bath  at  100°  C.  for 
an  hour  and  then  allow  the  ethereal  or  combined  sulphates  to 
settle. 

5.  The  Phosphates  consist  of  alkaline  and  earthy  salts  in  the 
proportion  of  2  to  i.  The  latter  are  insoluble  in  an  alkahne 
medium,  and  are  precipitated  when  the  urine  becomes  alkahne. 
They  are  insoluble  in  water,  but  soluble  in  acids ;  in  urine  they  are 
held  in  solution  by  free  COg.  The  alkaline  phosphates  are  very 
soluble  in  water,  and  they  never  form  urinary  deposits. 

The  composition  of  the  phosphates  in  urine  varies.  In  acid  urine,  the  acid 
salts  NaH.P04  and  Ca'H._.P04)2  are  generally  present.  In  neutral  urine  in 
addition  Na^HPOj,  CaHP04,  and  MgHPOi-  In  alkaline  urine  there  may  be 
also  NasPOj  Cas^POJj  Mg3(P04}2. 

6.  The  Earthy  Phosphates  are  phosphates  of  calcium  (Ca3P04)2 
(abundant)  and  magnesium  (scanty)  MgHPO^  +  yHgO.  Quantity 
I  to  1.5  grams  (15  to  23  grs.).  They  are  precipitated  when  the 
urine  is  alkahne,  although  not  in  the  form  m  which  they  occur  in 
the  urine  (Lesson  XVI.  11).  They  are  insoluble  in  water, 
readily  soluble  in  acetic  and  carbonic  acid,  and  are  precipitated  by 
ammonia. 

(«r/.)  To  clear  filtered  urine  add  nitric  acid,  boil,  and  add  baric 
chloride,  and  boil  again  =  a  precipitate  of  baric  sulphate.  Filter, 
and  to  the  cool  filtrate  add  ammonia  =  a  precipitate  of  baric 
phosphate. 

Clinical  Significance. — They  are  increased  in  osteomalacia  and  rickets,  in 
chronic  rheumatoid  arthritis,  after  prolonged  mental  fatigue,  and  by  food  and 
drink,  and  diminished  in  renal  diseases  and  phthisis. 

7.  The  Alkaline  Phosphates  are  chiefly  acid  sodium  phosphate 
(NaHqPO^),  with  traces  of  acid  potassium  phosphate  (KH0PO4);  they 


XVri.]         THE   INORGANIC   CONSTITUENTS   OF    URINE.  II 3 

are  soluble  in  water,  and  not  precipitated  by  alkalies,  and  nevei 
occur  as  urinary  deposits.  The  quantity  is  2  to  4  grams  (30  to 
60  grs.).  They  are  chiefly  derived  from  the  food,  and  perhaps 
a  small  amount  from  the  oxidation  of  the  phosphorus  of  nerve- 
tissues. 

(a.)  To  fresh,  clear-filtered  urine  add  ammonia,  caustic  soda,  or 
potash,  and  heat  gently  until  the  phosphates  begin  to  separate ;  let 
it  stand  for  some  time  =  a  white  precipitate  of  the  earthy  phosphates. 
Allow  it  to  stand,  and  estimate  approximately  the  proportion  of  the 
deposit.  [If  a  high-coloured  urine  be  used,  the  phosphates  may  go 
down  coloured,] 

(h.)  To  urine  add  about  half  its  volume  of  nitric  acid,  and  then 
add  solution  of  ammonium  molybdate  and  boil  =  a  canary-yellow 
crystalhne  precipitate  of  ammonium  phosplio-molybdate.  N.B. — 
The  molybdate  is  apt  to  decompose  on  keeping. 

(r.)  To  urine  add  half  its  volume  of  ammonia,  and  allow  it  to 
stand  =  a  white  precipitate  of  earthy  phosphates.  Filter  and  test 
the  filtrate  as  in  7  (/;.). 

(d.)  It  gives  the  reaction  for  phosphates.  This  method  separates 
the  alkaline  from  the  earthy  phosphates. 

(e.)  To  urine  add  half  its  volume  of  baryta  mixture  [Lesson 
XIX.  12  (c.)]  =  a  copious  white  precipitate.  Filter  and  test  the 
filtrate  as  in  7  (c).  It  gives  no  reaction  for  phosphoric  acid, 
showing  that  all  the  phosphates  are  precipitated. 

(/.)  To  urine  add  excess  of  ammonium  chloride,  and  ammonia 
=  a  white  precipitate  of  earthy  jihositJiatrs  and  oxalate  of  lime. 
Filter,  and  to  the  filtrate  add  a  solution  of  magnesic  sulphate  =  a 
precipitate  of  the  alkaline  phosphates  as  z'?'//>Zc^y//o,s;>/m/e.  If  the 
filtrate  be  tested  for  phosphoric  acid  by  7  {r.),  no  precipitate  will 
be  obtained. 

{(J.)  Instead  of  7  (/.),  use  magnesia  mixture,  composed  of 
magnesic  sulphate  and  ammonium  chloride,  each  i  part,  distilled 
water  8  parts,  and  liquor  ammonise  i  part.  It  gives  the  same 
result  as  in  7  (/.). 

Qi.)  To  urine  add  a  few  drops  of  acetic  acid,  and  then  uranium 
acetate  or  nitrate  =  bright  yellow  or  lemon-coloured  precipitate 
of  uranium  and  ammonium  double  phosphate — 2^U203)NH^P04. 
This  reaction  forms  the  basis  of  the  process  for  the  volumetric 
estimation  of  the  phosphoric  acid. 

The  other  fact  connected  with  the  volumetric  estimation 
of  phosphoric  acid  is,  that  when  a  uranic  salt  is  added  to  a 
solution  of  potassium  ferrocyanide,  a  reddish-brown  colour  is 
obtained. 

(^.)  To  a  very  dilute  solution  of  uranium  acetate  add  potassium 
ferrocyanide  =  a  brown  colour. 


114 


PRACTICAL   PHYSIOLOGY. 


[XVII. 


8.  In  some  pathological  urines  the  phosphates  are  deposited  on 
boiling. 

(a.)  Boil  such  a  urine  =  a  precipitate.  It  may  be  phosphates  or 
albumin.  An  albuminous  precipitate  falls  before  the  boiling-point 
is  reached,  and  phosphates  when  the  fluid  is  boiled.  Add  a  drop 
or  two  of  nitric  or  acetic  acid.  If  it  is  phosphates,  the  precipitate 
is  dissolved  ;  if  albumin,  it  is  unchanged. 

9.  Microscopic  Examination. — As  the  alkaUne  phosphates  are 
all  freely  soluble  in  water,  they  do  not  occur  as  a  urinary  deposit. 
The  earthy  phosphates,  however,  may  be  deposited. 

(a.)  Examine  a  preparation  or  a  deposit  of  calcic  phosphate, 
which  may  exist  either  in  the  amorphous  form  or  the  crystalline 
condition,  when  it  is  known  as  "stellar  phosphate"  (fig.  55). 

(6.)  Prepare  "  stellar  phosphate "  crystals  by  adding  some 
calcium  chloride  to  normal  urine,   and  then  nearly  neutralising. 


FlO.  55. — Stellar  Phosphate.  FlQ.  56. — Various  Forms  of  Triple  Phosphate. 

On  standing,  crystals  exactly  like  the  rare  clinical  form  of  stellar 
phosphate  are  obtained. 

(c.)  Triple  Phosphate  or  amraonio  -  magnesic  phosphate 
Mg(NH^)PO^  +  6H2O  never  occurs  in  normal  urine,  and  when 
it  does  occur,  indicates  the  decomposition  of  urea  to  give  the 
ammonia  necessary  to  combine  with  magnesium  phosphate  to  form 
this  compound.    It  forms  large,  clear  "  knife-rest"  crystals  (fig.  56). 

(d.)  If  ammonia  be  added  to  urine,  the  ammonio -magnesic 
phosphate  is  thrown  down  in  a  feathery  form,  which  is  very  rarely 
met  with  in  the  investigation  of  human  urine  clinically  (fig.  57). 

10.  General  Rules  for  all  Volumetric  Processes. 
(a.)  The  burette  must  be  carefully  washed  out  with  the  titrating 
solution,  and  must  be  fixed  vertically  in  a  suitable  holder. 


XVII.] 


THE   INORGANIC   CONSTITUENTS   OF   URINE. 


lis 


(b.)  All  air-bubbles  must  be  removed  from  the  burette  as  well  as 
from  the  outflow  tube.  The  latter  must  be  quite  filled  with  the 
titrating  solution. 

(c.)  Fill  the  burette  with  the  solution  up  to  zero,  and  always 
remove    the   funnel   with   which   it   is 
filled. 

(d.)  Read  off  the  burette  always  in 
the  same  manner,  and  always  allow  a 
short  time  to  elapse  before  doing  so, 
in  order  to  allow  the  fluid  to  run  down 
the  sides  of  the  tube. 

(e.)  The  titrating  fluid  and  the  fluid 
being  titrated  must  always  be  thoroughly 
well  mixed. 

(/.)  It  is  well  to  make  two  estima- 
tions,  the  first  approximate,   the  second  exact. 


Fig 


Feathery  Forms  of  Triple 
Phosphate. 


11.  Volumetric  Process  for  Phosphoric  Acid,  with  Ferrocy- 
anide  of  Potassium  as  Indicator. — i  cc  of  the  SS.  (Uranium 
acetate)  =  .005  gram  of  phosphoric  acid. 

Solutions  Eequired. — Sodium  Acetate  Solution. — Dissolve  100  grams  of 
sodium  acetate  in  100  cc.  pure  acetic  acid,  and  dilute  the  mixture  with  dis- 
tilled water  to  1000  cc. 

Potassium  Ferrocyanide  Solution.— Dissolve  i  part  of  the  salt  in  20  parts 
of  water. 

Uranium  Nitrate  Solution  (i  cc.  =.005  gram  H3PO4).— Dissolve  35  grama 
of  uranium  nitrate  in  strong  acetic  acid,  and  dilute  the  solution  to  i  litre. 

Apparatus  Required.  — Mohr's  burette, 
fitted  in  a  stand,  and  provided  with  a 
Mohr's  clip  ;  piece  ot  white  porcelain  ; 
tripod  stand  and  wire-gauze;  small  beaker; 
two  pipettes,  one  to  deliver  50  cc,  the 
other  5  cc. ;  glass  rod. 

(a.)  Collect  and  carefully  measure  ^ 
the  urine  passed  during  twenty-four 
hours. 

(h.)  Place  50  cc.  of  the  mixed 
and  filtered  urine  in  a  beaker.  Do 
this  with  a  pipette.  Place  the  beaker 
under  a  burette. 

(c.)  To  the  urine  add  5  cc.  of  the 
solution  of  sodium  acetate ;  mix 
thoroughly. 

(d.)  Fill   a   Mohr's  burette   with 
the  SS.  of  uranium  acetate  up   to    zero,   or  to   any  mark  on  tiie 
burette.       See    that   the    Mohr's  clip  is  tihgt,  and  that  the    out- 


FlO.  58.— Burette  ^[eniscns. 


ii6 


PRACTICAL   PHYSIOLOGY. 


[XVII. 


JLL 
/  \ 


flow  tube  is  filled  -vvith  the  SS.  Note  tlie  height  of  the  fluid 
in  the  burette.  Heat  the  urine  in  the  beaker  to  about  80°  C. 
Drop  in  the  SS.  ("  Standard  Solution  ")  of  uranium  acetate  from 
the  burette.  Mix  thoroughly.  Test  a  drop  of  the  mixture  from 
time  to  time,  until  a  drop  gives  a  faint  brown  colour 
when  mixed  with  a  drop  of  potassium  ferrocyanide. 
Do  this  on  a  white  plate. 

(p.)  Boil  the  mixture  and  test  again.  If  necessary, 
add  a  few  more  drops  of  the  SS.,  until  the  brown 
colour  reappears  on  testing  with  the  indicator. 
[Paper  may  be  dipped  in  the  indicator  solution  and 
tested  with  a  drop  of  the  mixture.]  Read  off'  the 
number  of  cc.  used. 


Example. — Suppose   17   cc.    of  the  SS.    are    required    to 

precipitate  the  phosphates  in  50  cc.   of  urine  ;   as  i  cc.  of 

SS.  =.005   gram   of   phosphoric   acid,    then   .005x17  =  .085 

gram  of  phosphoric  acid  in  50  cc.   of  urine.      Suppose  the 

patient  passed  1250  cc.  of  urine  in  twenty-four  hours,  then 

1250  X. 085  ^    ,       ,      .     . 

50  :  1250  :  :  .0S5  :  x — =2.12  grams  of  pnospnonc  m 

twenty-four  hours. 


12.  Reading  off  the  Burette. — In  the  case  of  the 
burette  being  filled  with  a  watery  fluid,  note  that  the 
upper  surface  of  the  water  is  concave.  Always  bring 
the  eye  to  the  level  of  the  same  horizontal  plane  as 
the  bottom  of  the  meniscus  curve.  Fig.  58  shows 
how  different  readings  may  be  obtained  if  the  eye  is 
placed  at  different  levels,  A,  B,  C. 


Fig.  59. 
Erdnianu's  Float 


13.  Erdmann's  Float  (fig.  59)  consists  of  a  glass  vessel 
loaded  with  mercury,  so  that  it  will  float  vertically.  It  is 
used  to  facilitate  the  reading  off  of  the  burette.  It  has  a  horizontal  line 
engraved  round  its  middle,  and  must  be  of  such  a  width  as  to  allow  it  just 
to  float  freely  in  the  burette.  Read  off  the  mark  on  the  burette  which 
coincides  with  the  ring  on  the  float. 

14.  Carlxjnates  and  bicarbonates  of  the  alkalies  are  generally  present  in 
alkaline  urine, and  are  most  abundant  in  the  urine  of  herbivora  and  vegetarians. 
They  are  derived  fi-om  the  oxidation  of  the  organic  vegetable  acids.  Car- 
bonate of  lime  is  not  normally  present  in  human  urine,  though  it  is  sometimes 
found  as  a  urinary  deposit. 

15.  The  Lime,  Magnesia,  Iron,  and  other  inorganic  urinary  constituents  are 
comparatively  unimportant,  and  have  no  known  clinical  significance. 


XVIII.]  ORGANIC   CONSTITUENTS  OF  THE   URINE.  117 


LESSON  XVIII. 

ORGANIC  CONSTITUENTS  OP  THE  URINE. 

1.  Urea  (CONoH^)  is  the  most  important  organic  constituent 
in  urine,  and  is  the  chief  end-product  of  the  oxidation  of  the 
nitrogenous  constituents  of  the  tissues  and  food.  It  crystallises 
in  silken  four-sided  prisms,  with  obliquely-cut  ends  (rhombic 
system),  and  when  rapidly  crystallised,  in  delicate  white  needles. 
It  has  no  effect  on  litmus ;  odourless,  weak  cool-bitter  taste,  like 
saltpetre.  It  is  very  soluble  in  water  and  in  alcohol,  and  almost 
insoluble  in  ether.  It  is  isomeric  with — z.e.,  it  has  the  same  empiri- 
cal, but  not  the  same  structural  formula  as  ammonium  cyanate 
(NHJCNO.     It  may 

be  regarded  as  a  diamid  of  CO2  or  as  carbamid  =  CO  I  tr-rT^* 

Urea  represents  the  final  stage  of  the  metamorphosis  of  albu- 
minous substances  within  the  body.  More  than  nine-tenths  of  all 
the  N  taken  in  is  excreted  in  the  form  of  urea. 


2.  Preparation  from  Urine. — Take  20  cc.  of  fresh  filtered  human 
urine,  add  20  cc.  of  baryta  mixture — Lesson  XIX.  12  (c.) — to  preci- 
pitate the  phosphates.  Filter,  evaporate  the  filtrate  to  dryness  in 
an  evaporating  chamber,  and  extract  the  residue  with  boiling  alco- 
hol. Filter  off  the  alcoholic  solution,  place  some  of  it  on  a  slide, 
and  allow  the  crystals  of  urea,  usually  long,  fine,  transparent 
needles,  to  separate  out.  This  is  best  done  by  allowing  spontaneous 
evaporation  of  the  solution  to  go  on  in  a  warm  place.  Examine 
them  microscopically  (fig.  60,  a). 

3.  Combinations. — Urea  combines  with  acids,  bases,  and  salts. 
Evaporate  human  urine  to  one-sixth  its  bulk,  and  divide  the  residue 
into  two  portions,  using  one  for  the  preparation  of  nitrate,  and  the 
other  for  oxalate  of  urea. 

4.  Urea  Nitrate  (CII4N2O,  HNO3). 

(a.)  To  the  concentrated  urine  add  strong  pure  nitric  acd  =  a 
precipitate  of  glancing  scales  of  urea  nitrate,  which,  being  almost 
insoluble  in  HNO.^^,  separate  out  in  rhombic  plates  or  six-sided 
tables,  with  a  mother-of-pearl  lustre,  and  often  imbricate  arrange- 
ment. 


i8 


PRACTICAL   PHYSIOLOGY. 


[XVIIL 


(h.)  Examine  the  crystals  microscopically  (fig.  60). 

(r.)  If  only  traces  of  urea  are  present,  concentrate  the  fluid 
supposed  to  contain  the  urea,  place  a  drop  on  a  slide,  put  into 
the  drop  one  end  of  a  thread,  apply  a  cover-glass,  and  put  a  drop 
of  2^ure  nitric  acid  on  the  free  end  of  the  thread.  The  acid  will 
pass  into  the  fluid,  and  microscopic  crystals  of  urea  nitrate  will 
be  formed  on  the  thread.  After  a  time  examine  the  preparation 
microscopically. 

5.  Urea  Oxalate  (CH^]Sr20)2  C^'Efi^  +  B.fi. 

(a.)  To  the  other  half  of  the  concentrated  urine  add  a  concen- 
trated solution  of  oxalic  acid.  After  a  time  crystals  of  oxalate  of 
urea  separate. 

(6.)  Examine  them  microscopically  (fig.  61). 


Fra.  60.— a.  Urea  ;  b.  Hexagronal  plates;  and  c.  Smaller  scales,  or  rhombic 
plates  of  urea  nitrate. 

(c.)  Add  oxalic  acid  to  a  concentrated  solution  of  urea  =  a  preci- 
pitate of  urea  oxalate,  which  may  have  many  forms — rhombic 
plates,  crystalline  scales,  easily  soluble  in  water. 

(d.)  Do  the  same  test  as  described  for  urea  nitrate  (4,  c),  but 
substitute  oxalic  for  the  nitric  acid. 

6.  Urea  and  Mercuric  Nitrate  (2CON2H4  +  Hg(N03)2  +  3HgO). 

(a.)  To  urine  (after  removing  the  phosphates  by  baryta  mixture) 
or  urea  solution  add  mercuric  nitrate  =  a  white,  cheesy  precipitate, 
a  compound  of  urea  and  mercuric  nitrate.  Liebig's  method  for  the 
estimation  of  urea  is  founded  on  this  reaction. 


xviil]       organic  constituents  of  the  urine.  119 

7.  other  Reactions  of  Urea.— IMake  a  strong  watery  solution 
of  urea,  and  Avitli  it  perform  the  following  tests  : — 

(a.)  Allow  a  drop  to  evaporate  on  a  slide,  and  examine  the 
crystals  which  form  (fig.  60,  a). 

(b.)  To  a  strong  solution  of  urea  add  ptii'e  nitric  acid  =  a  precipi- 
tate of  urea  nitrate  (fig.  60,  h). 

(('.)  To  a  strong  solution  of  urea  add  ordinary  nitric  acid  tinged 
yellow  with  iiitrous  acid,  or  add  nitrous 
acid  itself ;  bubbles  of  gas  are  given  off,  l® 

consisting  of  carbon  dioxide  and  nitro-     Q     fj  y~~ 


gen. 


(d.)  Add  caustic  potash,  and   heat.      The  »_m  ^ 

urea  is  decomposed,  ammonia  is  evolved,  and  ^    *^^  Q    ^^^\  ^ 
Ammonium   carbonate  is   formed  :— CON2H4  Q         *^  \         \  Q 

+  2H,0  =  (NH4)oCOo.  ^^.^     #s    \-^^ 


+  2H,0  =  (NH4)2CO 

(e.)  Mercuric  n: 
cheesy  prec-.pitate.  -a  ^^^        w  ^*  J< 


(e. )' Mercuric  nitrate  gives  a  greyish-white   _   i^S        I/  fl     ^\   v 


8.  With  Crystals  of  Urea   perform  ^^    ^ 

the  followit^g  experiments : —  ^^ 

(a.)  Biuret  Reaction.— Heat  a  crystal     ^  ^    x,    *.^   ,*    , 

.     ^     '  1      .    T  .1  ,1  1.  FlO.  61.— Crystals  of  Oxalate  of 

m   a   hard    tube;    the    crystal    melts,  urea from  Urine, 

ammonia  is  given  off,  and  is  recognised 

by  its  smell  and  its  action  on  litmus,  while  a  white  sublimate  of 
cyanuric  acid  (C3H3N3O3)  is  deposited  on  the  upper  cool  part  of 
the  tube.  Heat  the  tulDC  until  there  is  no  longer  an  odour  of 
ammonia.  Allow  the  tube  to  cool,  add  a  drop  or  two  of  water  to 
dissolve  the  residue,  a  few  drops  of  caustic  soda  or  potash,  and  a 
little  very  dilute  solution  of  cupric  sulphate  =  a  )nnk  colour  (biuret 
reaction).     T?ro  molecules  of  urea  yield  one  of  biuret. 

C0{NHLc0<^g2,jjjj 
(  NH  ~nO^  ^-L^^a 

C0|jjj|2     '-'^<NH2 

(6.)  Place  a  large  crystal  of  urea  in  a  watch-glass,  cover  it  with  a  saturated 
freshly  prepared  watery  solution  oifurfiirol,  and  at  once  add  a  droj)  ot  strong 
hydrochloric  acid,  when  there  occurs  a  rapid  i)lay  ot  colours,  beginning  with 
yellow  and  passing  through  green,  purple,  to  violet  or  brown.  This  test 
requires  care  in  its  performance. 

9.  Quantity. — An  adult  excretes  30  to  40  grams  (450  to  600 
grs.)  daily ;  a  woman  less,  and  children  relatively  more.  It  varies, 
however,  with 

(a.)  Nature  of  the  Food.— It  increases  when  the  nitrogenous  matters  are 


120  PRACTICAL  PHYSIOLOGY.  [XIX. 

increased  iu  the  food,  and  is  diminished  by  vegetable  diet.  It  is  increased 
by  copious  draughts  of  water,  salts.     It  is  still  excreted  during  starvation. 

(/'.)  Muscular  Exercise  has  little  clfect  on  the  amount, 

(c.)  In  Uisca^e, — In  the  acute  stage  of  fevers  and  inHaramation  there  is  an 
increased  formation  and  discharge,  also  in  saccharine  diabetes  (from  the  large 
quantities  ot  food  consumed).  It  is  diminished  in  ana?mia,  cholera,  by  the 
use  of  morphia,  in  acute  and  chronic  Bright's  disease.  If  it  is  retained  within 
the  body,  it  gives  rise  to  uritmia,  when  it  may  be  excreted  by  the  skin,  or  be 
given  oil  by  the  bowel. 

10.  Occurrence. — Urea  occurs  in  the  blood,  lymph,  chyle,  liver,  lymph 
glands,  spleen,  lungs,  brain,  saliva,  amniotic  fluid.  The  chief  seat  of  its 
fonnation  is  very  probably  the  liver.  It  also  occurs  in  small  quantity  in 
the  urine  of  birds,  reptiles,  and  herbivora,  but  it  is  most  abundant  in  that 
of  carnivora. 


LESSON  XIX. 
VOLUMETRIC  ANALYSIS  FOR  UREA. 

1.  Before  performing  the  volumetric  analysis  for  urea,  do  the 
following  reactions,  which  foiTti  the  basis  of  this  process  : — 

{'I.)  To  a  solution  of  sodic  carbonate  add  mercuric  nitrate  =  a 
yellow  precipitate  of  mercuric  hydrate. 

(A.)  To  urine  add  sodic  carbonate,  and  then  mercuric  nitrate  = 
first  of  all  a  white  cheesy  precipitate ;  on  adding  more  mercuric 
nitrate,  a  yellow  is  obtained,  ?.^.,  no  yellow  is  obtained  until  the 
mercuric  nitrate  has  combined  with  the  urea,  and  there  is  an  excess 
of  the  mercuric  salt. 

(c.)  To  urine  add  Jiypobroinife  of  soda.  At  once  the  urea  is 
decomposed,  and  bubbles  of  gas — N — are  given  off. 

2.  Estimation  of  Urea  by  Hiifner's  Hypobromite  Method. 

The  principle  of  this  method  depends  on  the  fact  that  urea  is 
decomposed  by  alkaline  solution  of  sodium  hypobromite,  yielding 
water,  CO.,  and  X.  The  CO.,  is  absorbed  by  tlie  caustic  soda,  the 
X,  which  is  disengaged  in  bubbles,  is  collected  and  measured  in  a 
suitable  apparatus. 

Sodium  Carbon  .Sodiuro 

Urea.  Hypobromite.        Dioxide.    Nitrogen.       Water,  Bromide. 

"  COXoH^   +    sXaBrO    =    CO.,   +   Xg   +    2H2O   +    sXaBr 

Every  o.i  gram  of  urea  contains  .046  gram  X;  this  at  tlie  ordi- 
nary temperature  and  pressure  =  37.3  cc.  of  nitrogen.  In  practice 
only  35.43  cc.  are  obtained.  It  is  an  accurate  method,  and  the 
one  generally  used  for  clinical  purposes.  Many  different  forms  of 
apparatus  have  been  devised,  including  those  of  Knop  and  Hiifner, 
Russel  and  "West,  Graham  Steele,  Simpson.  Dupre,  Charteris, 
Gerrard,  <fec. 


XIX.] 


VOLUMETRIC  ANALYSIS   FOR  UREA. 


121 


8.  Apparatus  and  Solutions  required. 

( i.  )  A  40  per  cent,  solution  of  caustic  soda. 

(  ii.)  Tubes  containing  2  and  4  cc.  of  bromine.     This  is  far  more  con- 
venient than  the  fluid  bromine, 
(iii. )  A  strong  glass  cylinder  with  a  glass  stopper, 
(iv.)  A  5  cc.  pipette. 
(  V. )  Urea  apparatus,  e.g.,  of  Dupre,  or  Gerrard. 

4.  Make  the.  hypohromite  solution :  Place  23  cc.  of  the  caustic  soda  solution 
in  the  glass-stop})ered  cylinder,  drop  into  it 
gently  a  tube  containing  2  cc.  of  bromine. 
Shake  the  cylinder  so  as  to  break  the 
bromine  tube  ;  the  soda  combines  with  the 
bromine.  These  bromine  tubes  can  bo 
purchased.  The  solution  spoils  by  keeping, 
so  that  it  should  be  made  fresh  for  each 
estimation. 


5.  Dupr^'s  Apparatus.! — In  this 
apparatus  (fig.  62)  the  graduation  on 
the  collecting  tube  represents  either 
the  percentage  of  urea  or  cc.  of  N. 
The  collecting  tube,  which  is  clamped 
above,  is  placed  in  a  tall  vessel  con- 
taining water,  and  connected  with  a 
small  glass  flask  containing  a  short 
test-tube. 

(a.)  Remove  the  short  test-tube 
from  the  flask,  and  in  the  latter 
place  25  cc.  of  the  hypohromite 
solution. 

(h.)  With  a  pipette  measure  off  5 
cc.  of  the  clear  filtered  urine,  and 
place  it  in  the  short  test-tube  attached 
to  the  india-rubber  stopper,  and  seen 
on  the  left  side  of  fig.  62.  This 
is  preferable  to  the  pipette  shown 
in  the  fig.  Place  the  caoutchouc 
stopper  in  the  flask. 

(r.)  Test  to  see  if  all  the  connec- 
tions are  tight.  Open  the  clamp  at 
the  upper  end  of  the  collecting  tube, 
depress  the  tube  in  the  water  until 
the  water  inside  and  outside  the  tube 
is  at  zero  of  the  graduation, 
collecting  tube. 


Fig.  6?.— Dupr^'s  Urea  Apparatus. 

Close  the   clamp,   and    raise   th 
If  the  apparatus  be  tight,  no  air  will  pass  in 


*  Made  by  George  J.  Smith,  73  Farringdon  Street. 


122 


PRACTICAL  PHYSIOLOGY. 


[XIX. 


and  on  lowering  the  collecting  tube  the  water  will  stand  at  zero 

inside  and  outside  the  tube. 

((f.)  Mix  the  urine  gradually  with  the  hypobromite  solution  by 
gently  tilting  over  the  flask.  Gas  is  rapidly  given  ofF,  the  COg  is 
absorbed  by  the  caustic  soda,  while  the  N  is  collected  in  the 
graduated  measuring  tube. 

(e.)  Place  the  flask  in  a  jar  of  water  at  the  same  temperature  as 
that  in  the  tall  jar,  and  slightly  lower  the  measuring  tube.     After 


FlO.  63.—  Steele's  Apparatus  for  Urea.    A.  Flask  for  hypobromite ;  B.  Tube  for 
urine ;  C.  Burette  ;  D.  Vessel  with  water ;  £.  Vessel  with  water  to  cool  A. 


all  eff'crvescence  has  ceased,  and  when  the  N  collected  in  the  col- 
lecting tube  has  cooled  to  the  temperature  of  the  room— i.e.,  in  five 
to  ten  minutes — raise  the  collecting  tube  until  the  fluid  inside  and 
outside  stands  at  the  same  level.  Eead  off"  the  graduated  tube; 
this  gives  the  percentage  of  urea.  Or  if  the  burette  be  graduated 
in  cc.  read  off"  the  number  of  cc.  and  calculate  the  amount  of  urea 
from  the  amount  of  N  evolved. 

It  is  to  be  remembered  that  other  bodies  in  the  urine,  such  as 
uric  acid  (urates)  and  kreatinin — but  not  hippuric  acid — also  yield 


XIX.] 


VOLUMETRIC  ANALYSIS   FOR   UREA. 


123 


nitrogen  by  this  process;  further,  that  only  about  92  per  cent, 
of  the  N  of  tlie  urea  is  given  off  in  the  above  processes.  These 
sources  of  fallacy  are.  however,  taken  into  account  in  graduating 
the  apparatus. 

6.  Steele's  Apparatus  (fig.  63). — In  this  apparatus  the  collect- 
ing tube  is  a  graduated  burette  graduated  in  cc. 

(a.)  Use  tliis  apparatus  in  a  similar  manner.     The  tube   B   is 
intioduced  into  the  flask  A  by  means  of  a 
pair  of  forceps.  ^k 

(b.)  Eead  off  the  number  of  cc.  of  N   '    ' 
evolved,    and    from    this    calculate    the 
amount  of  urea.     Every  35.4  cc.  N  =  o.i 
gram  urea. 

7.  Ureameter  of  Doremus  (fig.  64). — 
It  consists  of  a  graduated  bulb-tube,  closed 
at  one  end.  Hypobromite  of  sodium 
solution  is  poured  into  the  tube  up  to  a 


certain  mark. 


to 


I 


and  diluted  with  water 
fill  the  long  arm  and  bend.  The  urine 
to  be  tested  is  drawn  into  the  pipette  to 
the  graduation.  The  pipette  is  then  passed 
into  the  ureameter,  as  far  as  the  bend, 
and  the  nipple  is  compressed  slowly.  The 
urine  will  then  rise  through  the  hypo- 
bromite solution,  and  the  gas  evolved  will 
collect  in  the  upper  part  of  the  tube. 

Pkch   division   indicates  .001   gram   of 
urea  in  i  cc.  of  urine.     The  percentage  of  urea  present  in  the  urine 
is  found  by  simply  multiplying  the  result  of  the  test  by  100. 

8.  Study  also  Charteris's  apparatus.  The  bromine  and  caustic  soda  are 
mixed  in  a  marked  measure,  so  that  the  hypobromite  is  always  fresh,  while 
tlie  collecting  tube  for  the  N  is  so  graduated  as  to  indicate  a  certain  percentafe 
of  urea.  ^ 


¥lQ.  64. 


Ureameter  of  Doremus 
with  Pipette, 


9.  Study  Squibb's  apparatus. 
with  the  apparatus. 


In  all  these  cases  directions  are  supplied 


10.  Liebig's  Volumetric  Process  for  Urea  with  Sodic  Carbonate  as  Indi 
cator,  — I  cc.  of  the  SS.  (mercuric  nitrate)  =  .01  gram  or  10  milligrams  of  urea. 
This  method  has  been  largely  supplanted  by  the  hypobromite  process. 

11.  Solutions  Required. 

Baryta  Mixture.— Prepared  as  in  Lesson  XIX.  12  (r). 

Mercuric  Nitrate  Solution.— (i  cc.  =  -qi  gram  urea).  Dissolve  with  the 
aid  of  gentle  heat  77.2  grams  of  pure  dry  oxide  of  mercury  in  as  small  a 
quantity  as  possible  of  HNO3,  evaporate  to  a  syrup,  and  then  dilute  with 


124  PRACTICAL   PHYSIOLOGY.  [XIX. 

water  to  i  litre.     A  few  drops  of  HNO3  will  dissolve  any  of  the  basic  salt  left 
undissolved.     N.B. — The  exact  strength  of  this  solution  must  be  estimated 
by  titrating  it  with  a  standard  2  per  cent,  solution  of  urea, 
Sodic  Carbonate  Solution.  — 20  grains  to  the  ounce  of  water. 

12.  Apparatus  Eequired. — Burette  fixed  in  a  stand,  funnels,  beakers, 
filter-paper,  glass  rod,  plate  of  glass,  and  three  pipettes,  10,  15,  and  20  cc. 

{a. )  Collect  the  urine  of  the  twenty-four  hours,  and  measure  the  quantity. 

{b.)  If  albumin  be  present,  separate  it  by  acidification  (acetic  acid,,  boiling, 
and  filtration. 

(c.)  Mix  40  cc.  of  urine  with  20  cc,  i.e.,  half  its  volume,  of  a  solution  of 
barium  nitrate  and  barium  hydrate  (composed  of  one  volume  of  solution  of 
barium  nitrate  and  two  volumes  of  barium  hydrate,  both  saturated  in  the  cold). 
This  precipitates  the  phosphates,  sulphates,  and  carbonates. 

{d.  1  Filter  through  a  dry  filter  to  get  rid  of  the  above  salts.  While  filtra- 
tion is  going  on,  fill  the  burette  with  the  standard  solution  (SS.)  of  mer- 
curic nitrate  up  to  the  mark  0  on  the  burette.  See  that  there  are  no  air- 
bubbles,  and  that  the  outflow  tube  is  also  filled. 

(g.)  With  a  pipette  take  15  cc.  of  the  clear  filtrate  and  place  it  in  a  beaker. 
N.B. — This  corresponds  to  10  cc.  of  urine.  Place  a  few  drops  of  the  sodic 
carbonate  solution  (the  indicator)  on  a  piece  of  glass  resting  on  a  black  back- 
ground. 

(/.)  Note  the  height  of  the  fluid  in  the  burette.  Run  in  the  SS.  of  mer- 
curic nitrate  from  the  burette  into  the  15  c«.  of  the  mixture,  in  small 
quantities  at  a  time,  until  the  precipitate  ceases.  Stir  and  mix  thoroughly 
with  a  glass  rod.  After  each  addition,  with  the  glass  rod  lift  out  a  drop  of 
the  mixture  and  place  it  on  one  of  the  drops  of  sodic  carbonate  until  a  pale 
yelloic  colour  is  obtained.  This  indicates  that  all  the  urea  has  been  precipi- 
tated, and  that  there  is  an  excess  of  mercuric  nitrate.  Read  off  the  number 
of  cc.  of  the  SS.  used. 

(</. )  Repeat  the  experiment  with  a  fresh  1 5  cc.  of  the  filtrate,  but  run  in  the 
greater  part  of  the  requisite  SS.  at  once  before  testing  with  sodic  carbonate. 

Read  off  the  number  of  cc.  of  the  SS.  used,  and  deduct  2  cc. ;  multiply  by 
.01,  which  gives  the  amount  (in  grams)  of  urea  in  10  cc.  of  urine. 

Example.— Suppose  27  cc.  of  theSS.  were  used,  and  the  patient  passed  1200 
cc.  of  urine  in  twenty-four  hours:  then  25  x  .01  =  .25  gram   urea  in  10  cc. 

1200  X   .2C 

10  :  1200  : :  .25  :  x  .  —^ —  =  ^p  grams  of  urea  in  twenty-four  hours. 

This  method  yields  approximately  accurate  results  only  when  the  amount 
of  urea  is  about  2  ])er  cent.  With  a  greater  or  less  percentage  of  urea,  certain 
modifications  have  to  be  made. 

Correction  for  Sodic  Chloride. —Two  cc.  were  deducted  in  the  above  pro- 
cess. Why?  On  adding  mercuric  nitrate  to  a  solution  containing  sodic 
chloride,  the  mercuric  nitrate  is  decomposed  and  mercuric  chloride  formed, 
and  as  long  as  any  sodic  chloride  is  present,  there  is  no  free  mercuric  nitrate 
to  combine  with  the  urea      Proofs  of  this  : — 

(rt.)  To  a  solution  of  sodic  chloride  (normal  saline)  add  mercuric  nitrate  = 
no  precipitate. 

ib.)  To  a  solution  of  sodi'.  chloride  (normal  saline)  add  a  few  crystals  of  urea, 
then  add  mercuric  nitrate  At  first  there  is  no  precipitate,  or,  if  there  is, 
it  is  redissolved  ;  but  by-and-by  a  white  precipitate  is  obtained. 

(c)  To  a  solution  of  urea  (acid;  add  mercuric  chloride  =  precipitate. 


XIX.] 


VOLUMETRIC   ANALYSIS   FOR   UREA. 


125 


ADDITIONAL  EXERCISES. 

13.  Hiifner's  Apparatus  (fig.  65).— It  consists  of  a  stout  fusiform  glass 
cylinder  (B)  ^capacity  100  cc),  connected  below  by  means  of  a  glass  tap  with 
a  smaller  tube  (capacity  5  cc. ).  The  capacity  of  A  is  important,  as  it  contains 
the  urine,  so  that  it  must  be  previously  calibrated.     The  remainder  of  the 


Fig.  65.— Hiifner's  Urea  Apparatus. 

apparatus  consists  of  a  glass  bowl  (C)  fitted  by  means  of  a  caoutchouc  stopper 

upon  the  ui)per  end  of  B.     Above  this  is  a  graduated  gas-collecting  tube  (D),- 

40  cm.  long  and  2  cm.  wide,  and  graduated  into  0.2  cm.  in  units  of  cajiacity. 

By  means  of  a  long  funnel  fill  the  vessel  A  with  urine,  close  the  tap,  and 


126 


PRACrriCAL   PHYSIOLOGY. 


[XIX. 


wash  every  trace  of  urine  out  of  B.  Place  C  in  position,  fill  B  with  a  fi-eshly- 
pre{»areil  solution  of  hypobromite,  and  place  a  concentrated  solution  of  com- 
mon salt  in  C  to  the  depth  of  i  cm.  Fill  D  also  with  the  salt  solution, 
avoiding  the  presence  of  air-bubbles.  Insert  D  over  B.  Open  the  tap  when 
the  hypobromite  mixes  with  the  urine  and  tlie  gases  are  evolved.  The  quan- 
tity of  urea  is  calculated  from  the  volume  of  N  evolved. 

14.  Gerrard's  Apparatus  (fig.  66\ 

Mcthixl  of  Using.  —Pour  into  the  tube  5  cc.  of  the  urine  to  be  examined,  and 
in  the  bottle  [a)  25  cc.  or  6  fluid  drachms  of  sodium  hypobromite  solution. 
Place  the  tube  carefully  inside  the  bottle,  as  shown  in  the  illustration,  avoid- 
ing spilling  any  of  the  contents.     Fill  the  glass  tubes  {l\  c)  with  water,  so  that 

the  level  reaches  the  zero-line,  tak- 
ing care  that  when  this  is  done  the 
tube  {c)  contains  only  a  little  water 
by  being  placed  high — it  having  to 
receive  what  is  displaced  from  {h)  by 
the  nitrogen  evolved.  Now  connect 
the  india-rubber  tubing  to  the 
bottle,  and  noting  lastly  that  the 
water  is  exactly  at  zero,  upset  the 
contents  of  the  tube  into  the  hypo- 
bromite solution.  Nitrogen  is 
evolved,  and  depresses  the  water  in 
(Jb).  When  this  ceases,  lower  (r) 
nntil  the  level  of  the  water  in  both 
tubes  is  equal.  To  be  exact,  dip 
(a)  into  cold  water  to  cool  the  gas 
before  taking  a  reading,  and  note 
the  result,  which  shows  percentage 
of  urea. 

The  solution  of  hypobromite  of 
soda  is  made  by  dissolving  100 
grams  of  caustic  soda  in  250  cc.  of 
water,  then  adding  22  cc.  of 
bromine. 

To  avoid  the  danger  of  the  bro- 
mine vapour,  the  bromine  is  sold  in 
hermetically  sealed  glass  tubes,  con- 
taining 2.2  cc.  ;  one  of  these  })laccd 
in  the  large  bottle  with  25  cc.  of  the 
soda  solution  gives,  when  broken 
with  a  sharp  shake,  the  exact 
quantity  of  hypobromite  for  one  estimation  of  urea,  and  all  bad  odour  is 
avoided. 

15,  Synthetic  Preparation  of  Urea. — Heat  coarsely-powdered  ferro- 
cyanide  ot  potassium  (FeCy.,.4KCy +  3H.O,  about  250  grams)  over  a  fire  in  a 
large  porcelain  vessel.  Stir  constantly,  and  heat  until  the  whole  assumes  a 
white  colour,  and  the  larger  ])ieces  when  broken  up  show  no  trace  of  yellow. 
If  it  be  over-hciited  the  powder  becomes  brown.  The  white  mass  is  finely 
powdered  and  mixed  with  half  its  volume  of  dry,  finely-powdered,  black  oxide 
of  manganese.  The  whole  is  heated  in  a  black  metal  pot  in  a  draught 
chamber  until  it  begins  to  scintillate,  and  the  mass  becomes  doughy.  The 
mass  is  heated  until  a  small  portion  of  it,  when  dissolved  in  water  and  after 
acidulation  with  hydrochloric  acid,   is   no  longer  rendered  blue  by  ferric 


Fig.  66. — Gerrard's  Urea  .\pii:iratns,  as  ma- 
by  GibliS,  Cuxsi.n,  &  Co.,  \Vednesl)ury. 


XX.]  URIC   ACID,   ETC.  127 

chloride  Cool  and  extract  with  cold  water,  and  add  to  the  solution  dry 
ammonium  sulphate  to  the  extent  of  three-fourths  of  the  weight  of  potassic 
fenocyanide  used.  Filter,  evaporate  on  a  water-bath  at  about  60^-70^  C.  (at 
which  temperature  ammonium  cyanate  passes  into  urea).  At  first  potassic 
sulphate  crystallises  out ;  remove  it  from  time  to  time.  Lastly,  evai)orate  to 
dryness,  and  extract  the  urea  from  the  residue  by  absolute  alcohol.  The  urea 
crystallises  from  the  alcoholic  solution  at  a  moderate  temperature  {Drechsel). 

16.  Estimation  of  Total  Nitrogen  {PJluger  and  BohlancVs  Approximative 
M'thod.—{i.)  Take  10  cc.  of  urine,  add  Liebig's  mercuric  nitrate  until  a 
faint  yellow  is  obtained  with  a  drop  of  the  mixture  when  the  latter  is  tested 
with  sodic  carbonate.  The  number  of  cc.  of  the  SS.  used  multiplie<l  by  0.04 
gives  the  total  N". 

(ii.)  KjeldahVs  Method.— l^\i\^  method,  when  once  the  standardised  solutions 
are  prepared,  and  the  a])paratus  set  up,  can  be  carried  out  in  about  an  hour, 
and  several  estimations  can  be  carried  out  simultaneously.  In  this  method 
the  organic  matter  is  destroyed  by  prolonged  heating  of  the  substance  with 
sulphuric  acid  until  the  originally  blackish  fluid  becomes  clear  and  yellow 
coloured.  After  it  cools,  caustic  soda  is  added,  the  flask  is  corked,  and  the 
mixture  is  distilled,  whereby  the  ammonia  passes  over  into  a  standardised 
solution  of  sulphuric  acid.  The  ammonia  is  calculated  by  titrating  the 
sulphuric  acid  with  standard  caustic  soda.  (See  Sutton's  Volumetric  Aiialysis, 
p.  68,  5th  edit..  1886.) 


LESSON  XX. 

URIC  ACID— URATES— HIPPURIO  ACID  — 
KREATININ,  &c. 

1.  Uric  Acid  (C5H^N403)  contains  33.33  per  cent,  of  N,  and, 
next  to  urea,  is  the  constituent  of  the  urine  whereby  the  largest 
quantity  of  N  of  the  body  is  excreted,  whilst  in  birds,  reptiles, 
and  insects  it  forms  the  chief  nitrogenous  excretion.  The  propor- 
tion of  urea  to  uric  acid  is  45  :  i. 

The  following  structural  formula  show  its  relation  to  urea,  and  the  results 
ot  its  decomposition  : — 

NH— CO 

CO      C-NH 

I       II     >co 
NH    C-NH 

2.  Quantity. — 0.5  gram  (7-10  grs.)  daily.  It  is  dibasic,  colourless,  and 
crystallises,  chiefly  in  rhombic  plates,  and  when  the  obtuse  angles  are 
rounded  the  "whetstone"  form  is  obtained.  It  often  crystallises  s})on- 
tiineously  in  rosettes  from  saccharine  diabetic  urine.  It  is  tasteless,  reddens 
litmus,  and  is  very  insoluble  in  water  (18,000  parts  of  cold  and  15,000  of 
warm  water),  insoluble  in  alcohol  and  ether.  In  the  urine  it  occurs  chiefly  in 
the  form  of  acid  urates  of  soda  (C5H2N4O3,  HNa)  and  potash. 


128 


PRACTICAL  PHYSIOLOGY. 


[xx. 


(a.)  In  a  conical  glass,  add  5  parts  of  HCl  to  20  parts  of  urine, 
put  it  in  a  cool  place  for  twenty -four  hours.  Yellow  or  brownish- 
coloured  crystals  of  uric  acid  are  deposited  on  tlie  sides  of  the 
glass,  or  form  a  pellicle  on  the  surface  of  the  fluid  like  fine  grains 
of  cayenne-pepper.  Both  uric  acid  and  its  salts  (urates),  when 
they  occur  as  sediments  in  urine,  are  coloured,  and  the  colour  is 
deeper  the  more  coloured  the  urine.  The  slow  separation  of  the 
uric  acid  is  probably  due  to  the  presence  of  phosphatic  salts. 

(/>.)  Collect  some  of  the  crystals  and  examine  them  microscopi- 
cally. The  crystals  assume  many  forms,  but  are  chiefly  rhombic. 
They  may  be  whetstone,  lozenge-shaped,  in  rosettes,  quadrilateral 


Fig.  67.— Uric  Acid.    a.  Rhombic  tables  (whetstone  form);  6.  Barrel  f  >nn  ; 
e.  Sheaves;  d.  Rosettes  of  whetstone  crystals. 

prisms,  &c.  They  are  yellowish  in  colour,  although  their  tint  may 
vary  from  yellow  to  red  or  reddish-brown,  depending  on  the  depth 
of  the  colour  of  the  urine  (figs.  67,  68). 

(c.)  The  crystals  are  soluble  in  caustic  soda  or  potash.  Observe 
this  under  the  microscope. 

('!.)  "With  the  aid  of  heat  dissolve  some  serpent's  urine— which 
is  solid,  and  consists  chiefly  of  ammonium  urate — in  a  lo  per 
cent,  solution  of  caustic  soda.  Add  water,  and  allow  it  to  stand. 
Pour  off  the  clear  fluid,  and  precipitate  the  uric  acid  with  dilute 
hydrochloric  acid.     Collect  the  deposit  and  use  it  for  testing. 

3.  Reactions  and  Tests. 

(a.)  Murexide  Test. — Place  uric  acid  in  a  porcelain  capsule 
add  nitric  acid,  and  heat  gently,  taking  care  that  the  temperatur- 


XX.] 


URIC   ACID,  ETC. 


129 


is  not  too  high— not  above  40°  C.  Very  disagreeable  fumes  are 
given  off,  while  a  yellow  or  reddish  stain  remains.  Allow  it  to 
cool,  and  bring  a  rod  dipped  in  ammonia  near  the  stain,  or  moisten 
it  with  strong  ammonia,  when  a  pur_ple-red  colour  of  murexide, 
CsHs(NH,)N,0„  appears.  It 
turns  violet  on  adding  caustic 
potash. 

{h.)  Repeat  the  experiment, 
but  act  on  the  residue  with 
caustic  soda  or  potash,  when 
a  violet-blue  colour  —  dis- 
charged by  heat — is  obtained. 
The  latter  distinguishes  it 
from  guanin.  When  uric  acid 
is  acted  on  by  nitric  acid, 
alloxantin  (CgH^N^Oy)  is 
formed,  which,  on  being 
further  heated,  yields  alloxan 
(C4H2N2O4) ;  the  latter  strikes 
a  purple  colour — murexide— 
with  ammonia. 

(r  \    PlnPA     ^^r^o     t\n\c\     nr»     a  ^^0-  68.— Uric  kc\(\.     a.  Rhomboidal,  truncated, 

y.)    riace    uric    acia    on    a        hexahedral.an.llan.in.ited  crystals;  6.  Rhom- 

micrOSCOpiC  slide,  and  dissolve        biu  prism,  horizontally  truncated   angles  of 

if    iv^     li'o,,-./^--    •»%/^4-r.r,r,^        TJ"^«4-         ^^6  rhoinbic  prism  ;    c.  Prism  with  a  hexa- 

It    m    liquor    potaSSae.       Heat,        hedral  basic  surface,   barrel  -  shaped  figure, 

prism  with  a  hexahedral  basal  surface  ;  d. 
Cylindrical  figure,  stellate  and  superimposed 
groups  of  crystals. 


if  necessary;  add  hydro- 
chloric or  nitric  acid  just  to 
excess,  and  examine  with  the 
microscope  the  crystals  of  uric  acid  which  form. 


They  may  be 


transparent  rhombs  with  obtuse  angles,  dumb-bells,  or  in 
rosettes. 

{(1.)  Dissolve  uric  acid  in  caustic  soda,  add  a  drop  or  two  of 
Fehling's  solution — or  dilute  cupric  sulphate  and  caustic  soda — 
and  boil  =  a  white  precipitate  of  cupric  urate,  which  after  a  time 
becomes  greenish. 

(e.)  Schiff's  Test. — Dissolve  uric  acid  in  a  small  quantity  of 
sodium  carbonate.  Place,  by  means  of  a  glass  rod,  a  drop  of  solu- 
tion of  silver  nitrate  on  filter-paper,  and  on  this  place  a  drop  of  the 
uric  acid  solution.  A  dark  brown  or  black  spot  of  reduced  silver 
appears. 

(/.)  Heat  some  uric  acid  in  a  test-tube.  It  blackens  and  gives 
off  the  smell  of  burnt  feathers. 


{g.)  Garrod's  Microscopic  Test.— Add  6  to  8  drops  of  glacial  acetic  acid  to 
5  cc.  urine  in  a  watch-glass,  put  into  it  a  few  silk  threads,  and  allow  the 
whole  to  stand  for  twenty- four  hours,  taking  care  to  prevent  evaporation  by 

I 


130  PRACTICAL  PHYSIOLOGY.  [XX. 

covering  it  with  another  watch-glass  or  small  beaker.  Examine  the  threads 
microscopically  for  the  characteristic  crystals  of  uric  acid,  which  are  soluble 
in  KHO.     A  similar  reaction  may  be  done  on  a  microscopic  slide. 

4.  Uric  Acid  Salts  (Urates,  "  Lithates  "). — Uric  acid  forms  salts 
(cliiefly  acid),  with  various  bases,  which  are  soluble  with  difficulty 
in  cold,  but  readily  soluble  in  warm  water.  HCl  and  acetic  aci<l 
decompose  urates,  and  then  the  uric  acid  crystallises. 

Urates  form  one  of  the  commonest  and  least  important  deposits  in  urine. 
There  is  usually  a  copious  precipitate,  varying  in  colour  from  a  light  pink  or 
brick-red  to  purple.  They  occur  in  catarrhal  aflfections  of  the  intestinal  canal, 
after  a  debauch,  in  various  diseases  of  the  liver,  in  rheumatic  and  feverish 
conditions.  They  frequently  occur  as  the  "  milky  "  deposit  in  the  urine  of 
children.  Urates  constitute  the  "  lateritious"  deposit  or  "critical"  deposit 
of  the  older  writers.  Urates  frequently  occur  even  in  health,  especially  when 
the  skin  is  very  active  (in  summer^,  or  after  severe  muscular  exercise  ;  when 
much  water  is 'given  off  by  the  skin  and  a  small  quantity  by  the  kidneys. 
The  following  are  the  formulae  of  the  more  common  urates  : — 

Acid  sodic  urate CsR:i^iO:i'N&. 

Neutral  sodic  urate  ...  CgH-jN^OaNao. 

Acid  ammonium  urate     ....  C5H3N4O3' NH4). 

Acid  potassic  urate  ....  C5H3N4O3K. 

Wlien  the  urine  is  passed  it  is  quite  clear,  but  on  standing  for 
a  time  it  becomes  turbid,  and  a  copious  reddish-yellow — some- 
times like  pea-soup — or  purplish  precipitate  occurs,  because  urates 
are  more  soluble  in  warm  water  than  in  cold;  and  when  there 
is  only  a  small  quantity  of  water  to  hold  the  urates  in  solution, 
on  the  urine  cooling  they  are  precipitated.  Their  occurrence  is 
favoured  by  an  acid  reaction,  a  concentrated  condition  of  the  urine, 
and  a  low  temperature. 

The  urates  deposited  in  urine  consist  chiefly  of  sodic  ui-ate  mixed 
with  a  small  amount  of  ammonium  urate. 

5.  Tests  for  "  Urates  "  or  "  Lithates  "  in  urine. 

{a.)  Observe  the  naked-eye  characters.  The  deposit  is  usually 
copious  =  yellowish-pink,  reddish,  or  even  shading  into  piu-ple. 
The  deposit  moves  freely  on  moving  the  vessel,  and  its  upper 
border  is  fairly  well  defined. 

(h.)  Place  some  in  a  test-tube.  Heat  gently  the  upper  stratum. 
It  becomes  clear,  and  on  heating  the  whole  mass  of  fluid,  it  also 
becomes  clear,  as  the  urates  are  dissolved  by  the  warm  liquid. 

((.*.)  Place  some  of  the  deposit  on  a  glass  slide,  add  a  drop  of 
hydrochloric  acid,  and  uric  acid  is  deposited  in  one  or  more  of 
its  many  crystalline  forms.     Examine  the  crystals  microscopically. 

{fL)  Examine  the  deposit  microscopically.  The  urates  are 
usually  "  amorphous,"  but  the  urate  of  soda  may  occur  in  the  form 


XX.]  URIC   ACID,   ETC.  I3I 

of  small  spheres  covered  with  spines,  and  the  ammonium  urate,  of 
spherules  often  united  together  (fig.  77). 

(c.)  Make  a  saturated  solution  of  uric  acid  in  caustic  soda.  Place  a  drop 
of  the  mixture  on  a  slide,  allow  it  to  evaporate.  Examine  it  microscopically, 
when  the  urate  of  soda  in  the  form  of  spheres  covered  with  spines  will  be 
obtained. 

(/.)  The  same  result  as  in  {e.)  is  obtained  by  dissolving  the  ordinary  deposit 
of  urates  with  caustic  soda,  and  allowing  some  of  it  to  evaporate  on  a  slide. 

6.  Uric  Acid  from  Serpent's  Excrement. — Heat  the  powdered  excrement 
in  a  porcelain  vessel  with  15-20  vols,  of  water  just  to  boiling,  add  carefully 
small  quantities  of  caustic  potash  or  soda  until  the  whole  is  dissolved  and 
there  is  no  further  odour  of  ammonia  given  off.  Filter,  and  saturate  the 
filtrate  with  CCV>,  which  causes  at  first  a  gelatinous  and  tlien  a  finely-granular 
precipitate  of  acid  alkaline  urate.  Separate  the  latter  b}^  syphoning  off  the 
fluid,  wash  it  with  small  quantities  of  iced  water,  place  it  in  a  boiling  dilute 
solution  of  hydrochloric  acid,  and  boil  the  mixture  for  some  time.  After  it 
cools,  uric  acid  crystallises  out,  the  latter  is  washed  with  cold  water  and  dried. 

7.  Hippuric  Acid,  C^H^NOg  (benzoyl -amido- acetic  acid  or 
benzoyl-glycin). — This  substance  is  so  called  because  it  occurs  in 
large  quantity  in  the  urine  of  the  horse  and  many  herbivora, 
chiefly  in  the  form  of  alkaline  hippurates  (sodium  hippurate).  It 
belongs  to  the  aromatic  series.  It  dissolves  readily  in  hot  alcohol, 
but  is  sparingly  soluble  in  water. 

Quantity  in  man  .5  to  i  gram  daily.  It  is  a  conjugate  acid,  which,  when 
boiled  with  alkalies  and  acids,  takes  up  water  and  splits  into  benzoic  acid  and 
glycin.  It  occurs  in  colourless  four-sided  jjrisms,  usually  with  two  or  four 
bevelled  surfaces  at  their  ends.  It  has  a  bitter  taste.  Benzoic  acid,  oil  of 
bitter  almonds,  benzamid,  cinnamic  acid,  and  toluol  reappear  in  the  urine  as 
hippuric  acid.  The  benzoic  acid  unites  with  the  elements  of  glycocoll  (glycin), 
and  is  excreted  as  hippuric  acid  in  the  urine. 

Benzoic  Acid.  Glycocoll.         Hippuric  Acid.         Water. 

C7H0O.,     +     C.HsNO.,     =     CyHyNOa     -f     H,0. 

The  amount  is  increased  by  eating  pears,  a])ples  with  their  skins,  cranberries, 
and  plums.  Nothing  is  known  of  its  clinical  significance.  It  seems  to  be 
formed  chiefly  from  the  husks  or  cuticular  structures. 

Tests  and  Reactions. 

(a.)  Heat  some  crystals  in  a  dry  tube.  Oily  red  drops  are 
deposited  in  the  tube,  while  a  sublimate  of  benzoic  acid  and 
ammonium  benzoate  are  given  off.  The  latter  is  decomposed, 
giving  the  odour  of  ammonia,  while  there  is  an  aromatic  odour  of 
oil  of  bitter  almonds. 

{h.)  Examine  the  colourless  four-sided  prisms  with  the  micro- 
scope (fig.  69). 

(r.)  Boil  with  HNO3,  and  heat  to  dryness  ^  odour  of  nitrr»- 
benzene.     Benzoic  acid  gives  a  similar  reaction. 


132 


PRACTICAL  PHYSIOLOGY. 


[xx. 


8.  Preparation  of  Hippmic  Acid. — (<7.)  Take  loo  cc.  of  cow's 
or  horse's  urine,  and  evaporate  it  to  one-sixth  its  bulk ;  add  hydro- 
chloric acid,  and  set  it  aside.     The  brown  mass  is  collected,  dried 

between  folds  of  blotting- 
paper,  redissolved  in  a  very 
small  quantity  of  water,  and 
mixed  with  charcoal,  then 
filtered  and  set  aside  to 
crystallise.  It  is  not  quite 
pure  and  contains  a  brownish 
colouring-matter. 

(b.)  Boil  horse's  urine  with  milk 
of  lime  =  a  copious  precipitate. 
Filter  off  the  bulk  of  the  precipi- 
tate through  flannel,  and  filter 
again  through  paper.  Concentrate 
the  filtrate  to  one-sixth  of  its  volume  and  add  hydrochloric  acid  =  a  copious 
preci})itate  of  prismatic  crystals  of  hippuric  acid.  After  twenty-four  hours 
decant  the  fluid  from  the  crystals,  redissolve  the  latter  in  hot  water,  and  filter 
through  animal  charcoal. 


Fig.  69.— Hippuric  Acid. 


9.  Kreatinin  (C^H^NgO)  is  related  to  the  kreatin  of  muscle. 

If  kreatin  be  boiled  with  acids  or  with  water  for  a  long  time, 

it    loses   water,    and   becomes    converted  into    a    strong   base  — 
krsatinin. 

Quantity,  0.5  to  i  gram  (7  to  15  grs.).  It  is  easily  soluble  in  water  and 
alcohol,  and  forms  colourless  oblique  rhombic  crystals.  It  unites  with  acids, 
and  also  with  salts,  chiefly  with  ZnCL  ;  the  kreatinin-zinc-chloride  is  used  as 
a  microscopic  test  for  its  presence.  It  rarely  occurs  as  a  deposit,  and  nothing 
is  known  of  its  clinical  significance. 


10.  Preparation  of  Kreatinin.— (a.)  Take  250  cc.  of  urine,  precipitate  it  with 
milk  of  lime,  and  filter.  Evaporate  the  filtrate  to  a  syrupy  consistence,  and 
extract  it  with  alcohol.  Filter,  and  to  the  filtrate  add  a  drop  or  two  of  a 
neutral  solution  of  zinc  chloride,  and  set  the  vessel  aside.  After  a  time 
kreatinin-zinc-chloride  (C4H-N3O,  ZnCl.,)  is  deposited  on  the  sides  of  the  vessel. 

(6.)  To  half  a  litre  of  urine  add  baryta-mixture  (p.  124)  until  no  further 
precipitation  takes  place  ;  filter,  and  evaporate  the  filtrate  to  a  thin  syrup  on 
a  water-bath,  add  to  this  an  equal  volume  of  alcohol,  allow  it  to  stand  for 
twenty-four  hours  in  the  cold,  whereby  tlie  salts  are  separated,  filter,  and  to 
the  filtrate  add  1-2  cc.  of  a  concentrated  alcoholic  solution  of  zinc -chloride. 
After  a  time  kreatinin-zinc-chloride  separates  as  a  yellow  crystalline  powder. 
After  two  to  three  days  filter,  wash  with  alcohol,  and  dissolve  in  warm  water, 
and  decompose  it  by  boiling  for  half  an  hour  with  hydrated  lead  oxide 
or  carbonate  of  lead.  Filter  while  hot,  decolorise  the  filtrate  with  animal 
charcoal,  filter  again,  evaporate  to  dryness,  and  extract  the  kreatinin  from  the 
residue  with  alcohol  in  the  cold.  A  small  quantity  of  kreatinin  remains  un- 
dissolved. 


XX.J 


URIC   ACID,   ETC. 


133 


11.  Tests  and  Reactions  of  Kreatinin. 


(a.)  Jaffa's  Test. — Examine  the  deposit  of  the  zinc  compound 
microscopically.  It  forms  round  brownish  balls,  with  radiating 
lines  (fig.  70). 

(b.)  Weyl's  Test. — To  urine  add  a  very  dilute  solution  of  sodium 
nitro-prusside,  and  very  cautiously  caustic  soda  =  a  ruby-red  colour, 
which  lb  evanescent,  passing  into  a  straw  colour. 

(c.)  A  solution  of  kreatinin  reduces  an  alkaline  solution  of  cupric  oxide,  e.g., 
Fehling's  solution. 


FlO.  70.  — Ereatlnin-zinc-chloride.     a.  Balls  with  radiating  marks  ;  6.  Crystallised 
from  water ;  e.  Rarer  forms  from  an  alcoholic  extract. 

12.  Colouring-Matters  of  the  Urine. — (1.)  Normal  Urobilin, 

which  is  the  principal  colouring  matter  in  normal  urine.  Add  to 
urine  neutral  and  basic  lead  acetate  =  a  precipitate  of  lead  salts, 
which  carry  down  with  them  the  colouring  matter,  leaving  the 
solution  nearly  colourless.  Filter.  Extract  the  pigment  from  the 
filtrate  by  alcohol  acidulated  with  H2SO4.  Filter  =  alcoholic  extract 
of  deep  yellow  colour,  which  can  be  extracted  by  chloroform.  On 
evaporation  of  the  chloroform  it  is  deposited  as  a  yellow-brown 
mass,  which  in  an  acid  solution,  shows  with  the  spectroscope  one 
absorption  band  close  to  and  inclosing  F  at  the  junction  of  the 
blue  and  green.  On  adding  an  alkali  the  ])and  disappears 
{MacMunn).  Its  spectrum  and  composition  are  practically  identical 
with  choletelin  CigHjgN203,  and  it  is  regarded  as  an  iron-free 
derivative  of  haemoglobin  on  the  supposition  that  it  is  modified 


134  PRACTICAL  PHYSIOLOGY.  [XX. 

bile-pigment  absorbed  from  the  intestinal  canal  and  excreted  by 
the  urine, 

(2.)  [Febrile  Urobilin. —This  gives  the  dark  colour  to  urines  in  fever.  It 
seems  to  be  a  less  oxidised  form  of  urobilin,  is  isolated  in  the  same  way,  its 
spectrum  shows  the  band  near  F,  and  two  additional  bands,  one  near  D  and 
one  between  D  and  E.] 

(3.)  Indigo-forming  Substance  (Indican). — This  is  derived  from  indol, 
C8H7N,  which  is  developed  in  the  intestinal  canal  from  the  pancreatic  diges- 
tion of  proteids,  and  also  from  the  ])utrefaction  of  albuminous  bodies.  It  may 
also  be  formed  from  bilirubin.  In  urine  it  is  a  yellow  pigment,  and  is  more 
plentiful  in  the  urine  of  the  dog  and  horse.  It  exists  in  the  urine  as  a 
conjugated  sulpho-acid  salt  of  potassium,  viz.,  as  indoxyl-sulphate  of  potas- 
sium (CBHeNSO.K). 

13.  General  Reactions  for  Urine  Pigments. 

(a.)  Add  to  normal  urine  a  quarter  of  its  volume  of  HCl,  and 
boil  =  a  fine  pink  or  yellow  colour. 

(h.)  Add  nitric  acid  =  a  yellowish- red  colour,  usually  deeper  than 
the  original  colour. 

(c.)  To  two  volumes  of  sulphuric  acid  in  a  test-tube  add  one  of 
urine,  but  drop  the  latter  from  a  height.  The  mixtu^  becomes 
more  or  less  garnet-red  if  indican  be  present. 

(d.)  Add  acetate  of  lead  =  a  precipitate  of  chloride,  sulphate,  and 
phosphate  of  lead.  Filter ;  the  filtrate  is  an  almost  colourless 
solution.  This  substance  is  used  to  decolorise  urine  for  the  sac- 
charimeter. 

(e.)  Filter  urine  through  animal  charcoal;  the  urine  will  be 
decolorised. 

(/.)  If  possible,  obtain  a  dark-yellow  coloured  urine,  and  perform  the 
following  test  :  — Take  40  drops  of  urine +  3  to  4  cc.  of  strong  HCl  and  2  to  3 
drops  of  HNO3  ;  on  heating,  a  violet  red  colour  with  the  formation  of  true 
rhombic  crystals  of  indigo-blue  indicates  the  presence  of  indican. 

(f/.)  Test  for  Indican. — Mix  equal  volumes  of  urine  and  HCl,  add,  drop  by 
drop,  a  saturated  solution  of  chloride  of  lime  {i.e.,  bleaching  powder,  which 
also  contains  hypochlorite  of  calcium)  =  a  blue  colour.  Shake  up  with  chloro- 
form and  the  blue  colour  is  absorbed  by  the  latter. 

14.  Phenol  (carbolic  acid),  CeH,;0,  occurs  in  the  urine  as  phenol-sulphate  of 
potassium,  CuHjO  -  SO3  — OK.  There  is  a  corresponding  salt  of  Cresol,  most 
abundant  in  the  urine  of  herbivora.  Add  sulphuric  acid  to  urine  until  the 
latter  contains  5  per  cent,  of  the  acid.  Distil  as  long  as  the  distillate  becomes 
cloudy  with  bromine  water.     Test  the  distillate  as  follows  :  — 

(a.)  Bromine  water  =  precipitate  of  tri-bromo-phenol  (CgH-^BrgOH). 

{b.)  Neutralise  and  add  neutral  ferric  chloride  =  violet  colour. 

(c. )  Heated  with  Millon's  reagent  it  gives  a  red  colour.     (See  also  p.  82.) 

The  pathological  pigments — bile,  blood,  &c. — occurring  in  urine 
will  be  referred  to  later. 


XX.]  URIC   ACID,  ETC.  135 

15.  Mucus. — A  trace  of  mucus  occurs  normally  in  urine.  Col- 
lect fresh  urine  in  a  tall  vessel,  and  allow  it  to  stand  for  some 
time,  when  fine  clouds  ("  mucous  clouds ")  like  delicate  cotton- 
wool appear.  These  consist  of  mucus  entangling  a  few  epithelial 
scales. 

(a.)  If  the  urine  contain  an  excess  of  mucus,  on  adding  a  satu- 
rated solution  of  citric  acid  to  form  a  layer  at  the  bottom  of  the 
test-tube,  a  haziness  at  the  hne  of  junction  of  the  urine  and  acid 
indicates  mucus.  There  is  no  deposit  with  healthy,  freshly-passed 
urine.     Citric  acid  is  used  because  it  is  heavier  than  acetic. 

16.  Ferments  in  Urine. — There  is  no  doubt  that  urine  contains 
pepsin.  Some  observers  state  that  it  also  contains  trypsin  and  a 
sugar-forming  ferment ;  but  the  latter  statement  is  denied. 

(a.)  Select  the  morning  urine,  place  in  it  for  several  hours  fresh 
well-washed  and  boiled  fibrin.  The  latter  absorbs  the  ferment, 
and  on  placing  it  in  .2  per  cent.  HCl  at  40°  C,  the  pepsin  is 
dissolved  and  peptones  are  formed.  Test  for  the  peptones  by  the 
biuret  reaction. 

17.  Reactions  of  Normal  TJrine  towards  Reagents. 

(i.)  Add  5  cc.  of  HCl  to  100  of  urine.  After  twenty-four  hours  crystals  of 
uric  acid  separate  out. 

(2.)  Add  caustic  soda  or  ammonia  =  precipitate  of  the  phosphates  of  the 
alkaline  earths,  partly  in  an  amorphous  state,  partly  in  acicular  crystals. 

(3.)  Acidulate  with  nitric  acid  and  heat  with  phospho-molybdic  acid  =  blue 
coloration  due  to  urates. 

(4.)  Add  mercuric  nitrate  =  white  cloudiness,  which-disappears  on  shaking. 
This  is  a  precipitate  due  to  the  formation  of  sodium  nitrate  and  mercuric 
chloride  (Hg(N03)2  -f-  2NaCl  =  2N"aN03  +  HgCl.^),  soluble  in  acid  urine.  After 
all  the  NaCl  is  decomposed — but  not  until  then — a  permanent  precipitate,  a 
compound  of  urea  and  the  mercury  salt,  forms. 

(5. )  Silver  nitrate  =  white  precipitate  of  AgCl  and  Ag3P04  ;  the  latter  falls 
first,  and  afterwards  all  the  silver  combines  with  the  chlorine.  The  precipi- 
tate is  insoluble  in  HNO3  but  soluble  in  NH4HO. 

(6.)  Barium  chloride  -  white  precipitate  ofBaS04  and  Ba.{(P04)2. 

(7.)  Lead  acetate = whitish  precipitate  of  PbS04,  PbClg,  Pb3(P04)2,  and  the 
pigments. 

(8.)  Ferric  chloride  after  acidulation  with  acetic  acid  =  precipitate  of 
Fe,(P04)2.  ,    ,      ,    .    . 

(9.)  An  ammoniacal  solution  of  cupric  oxide  is  decomposed  and  decolorised 
at  the  boiling-point  by  the  urates. 

(10.)  Tannic  acid  =  no  precipitate  {Krukenlerg), 

18.  Estimation  of  Uric  Acid. — This  is  sometimes  done  by  the  method  (2,  «), 
but  it  is  not  accurate,  {a. )  Haycraf t's  Method  depends  on  the  formation  of  urate 
of  silver,  which  is  practically  insoluble  in  water  or  acetic  Ticid  {British  Medical 
Journal,  1885).  The  urate  of  silver  is  of  a  slimy  nature  and  must  be  washed 
on  an  asbestos  filter.  The  titration  of  the  silver  compound  is  by  means  of 
Volhard's  ammonium  thio-cyanate  method  (Sutton'g  Volumeiric  Analysis,  5th 
edit.,  1886,  pp.  116,  324). 


36 


PRACJTICAL  PHYSIOLOGY 


[XXI. 


(b.)  Hopkin's  Method.— Satnrate  the  fluid  with  crystals  of  ammonium 
chloride  =  ammonium  urate.  Collect  the  precipitate  and  dissolve  it  in  weak 
alkali.  Reprecipitate  by  HC1  =  precipitate  of  uric  acid,  which  is  dried  and 
weighed. 

19.  Average  Amount  of  the  Several  Urinary  ComtUuents  Passed  in  Tiventy- 
four  Hours  by  a  Man  Weighing  66  kilos. 


Water    . 
Total  solids 


Organic  solids —  Grams, 

ijrea         ....     33.18 

Uric  acid 55 

Hippuric  acid  .        .        .        .40 
Kreatinin  .         ,         .         .91 

Pigment  and  other  sub- 
stances.       •        •        •     10.00 


Grams. 
.     1500 
72 

Inorganic  solids — 
Sulphuric  acid 
Phosphoric  acid 
Chlorine 
Ammonia 
Potassium 
Sodium  . 
Calcium 
Magnesium 


Grams. 
2.01 
3.16 
7.00 
0.77 
2.50 
11.09 
0.26 
0.21 
—Parket, 


LESSON  XXL 


ABNORMAL  CONSTITUENTS  OP  THE  URINB. 

Some  of  the  substances  referred  to  iii  the  subsequent  lessons  are 
present  in  excessively  minute  traces  in  normal  urine — e.g.^  sugar ; 
and  in  the  urine  of  a  certain  percentage  of  persons  appar- 
ently enjoying  perfect  health,  minute  traces  of  albumin  are  some- 
times present.  "When,  however,  these  substances  occur  in  con- 
siderable quantity,  then  their  presence  is  of  the  utmost  practical  and 
diagnostic  value,  and  is  distinctly  abnormal.  It  is  quite  certain 
that  serum-albumin  is  never  found  in  any  considerable  amount  in 
normal  urine. 

1.  Albumin  in  Urine. — When  albumin  occurs  in  notable  quantity 
in  the  urine,  it  gives  rise  to  the  condition  known  as  albuminuria. 
Albuminous  urine  is  not  unfrequently  of  low  s.g.,  and  froths 
readily. 

Various  forms  of  proteid  bodies  may  occur  in  the  urine.  ITie 
chief  one  is  serum-albumin;  but,  in  addition,  serum-globulin, 
albumose,  peptone,  acid-albumin,  and  fibrin  may  be  found. 

2.  Tests. — In  every  case  the  urine  must  be  clear  before  testing, 
which  can  be  secured  by  careful  filtration. 

(a.)  Coagulation  by  Heat. — If  the  urine  is  acid  place   10  cc. 


XXI.]  ABNORMAL  CONSTITUENTS  OF  THE   URINE.  1 37 

of  urine  in  a  test-tube  and  boil.  Near  the  boiling-point,  if  albumin 
be  present  in  small  amount,  it  will  give  a  haziness ;  if  in  large 
amount,  a  distinct  coagulum.  On  standing,  the  coagulum  is 
deposited.  Some  prefer  to  boil  the  top  of  a  long  column  of 
urine  in  a  test-tube.  If  the  urine  be  acid,  then  any  haziness 
formed  is  readily  seen  against  the  clear  subnatant  fluid. 

Precautions.— (i.)  Always  test  the  reaction  of  the  urine,  for  albumin  is  only 
precipitated  by  boiling  in  a  neutral  or  acid  medium.  Hence  if  the  urine  be 
alkahne,  boihng  will  not  i)recipitate  any  albumin  tliat  may  be  j)rescnt.  (ii.) 
Boil  the  upper  stratum  of  the  fluid  first  of  all,  holding  the  tube  obliquely, 
taking  care  that  the  coagulum  does  not  stick  to  the  glass,  else  the  tube  is 
liable  to  break,  (iii.)  Heat,  by  driving  off  the  CO.2,  also  precipitates  m?-//rv 
phoaphafes  if  they  are  present  in  large  amoimt,  hence  a  turbidity  on  boiling 
is  not  sufficient  proof  of  the  presence  of  albumin.  The  points  of  distinction 
are,  that  albumin  goes  down  before  the  boiling-point  is  reached  (coagulated 
at  75°  C),  while  phosphates  are  precipitated  at  the  boiling-point.  Again, 
the  phosphatic  deposit  is  soluble  in  an  acid — e.g.,  acetic  or  nitric— while  the 
albuminous  coagulum  is  insoluble  in  these  fluids.  Some,  therefore,  advise 
that  the  test  be  done  in  the  following  manner  : — 

(b.)  Acidulate  the  urine  with  a  few  drops  of  dilute  acetic  or 
nitric  acid,  and  then  boil.  If  nitric  acid  be  used,  add  one-tenth  to 
one-twentieth  of  the  volume  of  urine. 

Precautions.  — If  the  urine  contain  only  very  minute  traces  of  albumin,  the 
latter  may  not  be  precipitated  if  too  much  nitric  acid  be  added,  as  the  acid 
albumin  is  kept  in  solution.  If  too  little  acid  be  added,  the  albumin  may  not 
be  precipitated,  as  only  a  part  of  the  basic  phosphates  are  changed  into  acid 
phosphates,  and  the  albumin  remains  in  solution  as  an  albuminate  (a  com- 
pound of  the  albumin  with  the  base).  On  heating  the  urine  of  a  person  who 
is  taking  copaiba,  a  deposit  may  be  obtained,  but  its  solubility  in  alcoliol  at 
once  distinguishes  it  from  coagulated  albumin.  This  test  acts  with  serum- 
albumin  and  globulin,  and  if  the  deposit  occurs  only  after  cooling,  also  with 
albumose,  but  not  with  peptone. 

(c.)  Heller's  Cold  Nitric  Acid  Test.— Take  a  conical  test-glass, 
and  place  in  it  15  cc.  of  the  urine.  Incline  it,  and  pour  slowly 
down  its  side  strong  nitric  acid  =  a  white  cloud  at  the  line  of 
junction  of  the  fluids. 

Precautions.— A  crystalline  deposit  of  urea  nitrate  is  sometimes,  though 
very  rarely,  obtained  with  a  very  concentrated  urine.  If  the  urine  contain  a 
large  amount  of  urates,  they  may  be  deposited  by  the  acid,  but  the  deposit  in 
this  case  occurs  above  the  line  of  junction,  and  disappears  on  heating.  It  is 
not  obtained  if  the  urine  be  diluted  beforehand. 

{d.)  Acidulate  10  cc.  of  urine  with  acetic  acid,  add  one-fifth  of  its  bulk  of  a 
saturated  solution  of  magnesium  or  sodium  sulphate,  and  boil  =  a  precipitate. 

(e.)  Acetic  Acid  and  Potassium  Ferrocyanide. — Acidify  strongly  with 
acetic  acid,  and  add  a  solution  of  potassium  ferrocyanide  =  a  white  precipi- 
tate, varying  in  amount  with  the  albumin  present.  The  reaction  may  be 
done  as  follows  : — Mix  a  few  cc.  of  moderately  strong  acetic  acid  with  some 
solution  of  potassium  ferrocyanide,  and  })our  this  over  some  urine  in  a  test-tuba 


138  PRACTICAL  PHYSIOLOGY.  [XXL 

by  the  contact  method  ('/.)•  Tlie  presence  of  albumin  is  indicated  by  a  white 
deposit  in  the  form  of  a  ring  at  the  line  of  junction  of  the  fluids.  A  solution 
of  platino  potiissium  cyanide  may  be  used  instead  of  the  ferrocyanide.  The 
solution  of  the  former  is  colourless.  This  test  precipitates  serum-albumin, 
globulin,  albumose,  but  not  peptone. 

( f.)  Picric  Acid. — Use  a  saturated  watery  solution,  and  apply  it 
by  the  contact  method  of  Heller  ('•.).  The  urine  is  below,  and  the 
picric  acid  on  the  top.  A  rapidly-formed  deposit  at  the  line  of 
junction  of  the  fluids  indicates  the  presence  of  a  proteid ;  the 
deposit  is  not  dissolved  by  heat. 

N.B. — Picric  acid  precipitates  all  the  forms  of  proteid  which  occur  in  urine. 
It  also  precipitates  mucin,  but  in  this  case  the  deposit  usually  forms  slowly 
and  after  a  time.  If  a  person  be  taking  quinine,  a  haziness  is  obtained  in  the 
urine  on  adding  piciic  acid,  but  it  disappears  on  heating.  Dr.  Johnson  and 
Professor  Grainger  Stewart  recommend  it  as  one  of  the  most  reliable  tests  for 
albumin  we  possess, 

((/. )  Metaphosphoric  Acid  completely  precipitates  albumin,  but  it  must  be 
freshly  prepared,  and  is  diflBcult  to  keep.     Hence  it  is  not  satisfactory. 

(h.)  Acidulated  Brine,  as  suggested  by  Roberts,  consisting  of  a  saturated 
solution  of  sodium  chloride  with  5  per  cent,  of  dilute  hydrochloric  acid  (B.P.), 
may  be  used,  but  it  sometimes  gives  a  precipitate  with  normal  urine.  Nor  is 
potassio-mercuric-iodide  satisfactory  ( Tauret).  In  cases  of  doubt,  use  several 
tests,  especially  2  (b.),  (c),  (e.),  and  (/.). 

(i.)  Trichloracetic  Acid  precipitates  albumin  iu  urine. 

(_;.)  Salicyl-Sulphonic  Acid  gives  a  white  precipitate  with  proteids,  which 
is  soluble  on  heating  in  the  case  of  albumose  and  peptone  (Ji*  William). 

3.  Dry  Tests. 

(a.)  Use  the  ferrocyanic  pellets  introduced  by  Dr.  Pavy. 
{b.)  Use  the  test-papers — citric  acid  and  ferrocyanide  of  potassium — intro- 
duced by  Dr.  Oliver. 

4.  Globulinuria. — Serum-globulin  is  present  in  nearly  every 
albuminous  urine.     It  gives  the  reactions  described  under  2. 

(rt.)  Fill  a  tall  glass  with  water.  Drop  the  urine  into  the  Avator, 
and  observe  if  a  milkiness  is  seen  in  the  water,  indicating  the 
presence  of  a  globulin.  This  body  is  not  soluble  in  pure  water, 
but  in  weak  saline  solutions  (Lesson  I.  6),  hence  on  diluting  the 
urine  it  is  precipitated. 

{h.)  Test  the  urine  by  the  contact  method  with  a  saturated  solu- 
tion of  magnesic  sulphate. 

(c.)  'J  his  body  is  completely  precipitated  on  saturating  the  urine 
with  ammonium  sulphate. 

If  globulin  be  present  along  with  serum-albumin  add  an  equal 
volume  of  a  saturated  solution  of  ammonium  sulphate.  A  white 
flocculeut  precipitate  indicates  globulin. 


XXL] 


ABNORMAL  CONSTITUENTS  OF  THE   URINE. 


139 


6.  Albumosuria. — Hemi-albumose,  which,  however,  is  really  a  mixture  of 
three  different  proteids,  has  been  found  in  cases  of  osteomalacia.  If  such  a 
urine  can  be  procured,  do  test  2  {b.),  using  nitric  acid  ;  the  deposit  only  takes 
place  after  a  long  time  or  on  cooling,  and  in  fact  the  urine  sometimes  becomes 
almost  solid,  but  is  dissolved  by  heat.  If  there  is  a  deposit,  filter  and  test  the 
filtrate  for  proteid  reactions,  e.(j.,  the  biuret  test.  It  will  give  a  precipitate 
with  acetic  acid  and  potassic  ferrocyanide.  Then  saturate  a  portion  of  the 
nrine  with  sodium  chloride,  and  acidify  with  acetic  acid  =  a  precipitate,  which 
dissolves  on  adding  much  acetic  acid  and  heating,  and  reappears  on  cooling 
(p.  73)- 

6.  Peptonuria. — Peptone  is  frequently. present  in  albuminous  urine.  Pep- 
tone is  most  frequently  present  in  urine  in  cases  where  there  is  an  accumula- 
tion and  breaking  up  of  leucocytes  or  pus-corpuscles,  as  in 

the  stage  of  resolution  of  pneumonia,  suppurative  processes, 
and  in  other  diseases.  Procure  such  a  urine.  It  is  well  to 
get  rid  of  the  albumin  by  acidification  with  acetic  acid  and 
boiling. 

(a.)  Put  some  urine  in  a  test-tube,  and  by  the  contact 
method  pour  on  some  Fehling's  solution.  At  the  line  of 
junction  a  phosphatic  cloud  is  formed,  and,  if  peptones  be 
present,  above  it  a  rose-pink  colour.  If  albumin  also  be  pre- 
sent, a  violet  colour  is  obtained.  Hemi-albumose  gives  the 
same  reaction. 

7.  Quantitative  Estimation  of  Albumin. — This  can  only  be 
done  accurately  by  precipitating  the  albumin,  drying  and 
weighing  it ;  but  as  this  is  a  tedious  process,  and  requires 
much  time,  it  is  not  suitable  for  the  physician. 

8.  Esbach's  Albmninimeter  (fig.  71). 

A.  The  Reagent. — rDissolve  10  grams  of  picric  acid 
and  20  grams  of  citric  acid  in  800  cc.  of  boiling  water, 
and  make  up  the  solution  to  a  litre. 

Dr.  Johnson  finds  that  a  solution  of  picric  acid  in 
boiling  water  (5  grains  to  the  ounce)  gives  the  same 
result. 

B.  Process. — Pour  urine  into  the  tube  (6  inch  x  f 
inch)  up  to  the  mark  U,  then  the  reagent  up  to  the 
mark  K,  mix  thoroughly.  Set  the  tube  aside  for 
twenoy-four  hours,  and  then  read  off  on  the  scale  the 
height  of  the  coagulum.  The  figures  indicate  the  na.  71. 
grams  of  dried  albumin  in  a  litre  of  urine — i.e.^  the  Esbach's  Tube, 
percentage  is  obtained  by  dividing  by  ten.     If  the 

coagulum  is  above  4,  or  if  the  original  s.g.  of  the  urine  is  above 
1010,  dilute  the  urine  first  with  one  or  two  volumes  of  water,  and 
then  multiply  the  resulting  figure  by  2  or  3  as  the  case  may  be.  If 
the  urine  be  alkaline,  it  must  first  be  acidulated  by  acetic  acid. 
If  the  amount  of  albumin  be  less  than  0.5  grams  per  litre,  it 
cannot  be  accurately  estimated  by  this  method. 


140  PRACTICAL  PHYSIOLOGY.  [XXII. 

LESSON  xxn. 

BLOOD,  BILE,  AND  SUGAR  IN  URINE. 

1.  Blood  in  Urine  (Haematuria). 

The  Blood  may  come  from  any  part  of  the  urinary  apparatus. 

If  from  kidney,  it  is  usually  small  in  amount  and  well  mixed  with  the 
urine,  and  the  microscope  may  reveal  the  presence  of  "blood-casts,"  i.e., 
Dlood-moulds  of  the  renal  tuhides.  Large  coagula  are  never  found,  and  the 
urine  not  unfrequently  is  '"smoky."  From  the  bladder  or  urethra,  usually 
the  urine  is  bright  red,  and  relatively  large  coagula  are  frequently  present. 
In  all  forms,  blood-corpuscles  are  to  be  detected  by  the  microscope,  and 
albumin  by  its  tests. 

{a.)  Examine  the  naked-eye  characters  of  a  specimen.  It  may 
be  any  tint  from  red  to  brown,  but  if  the  blood  is  well  mixed  witli 
the  urine,  the  latter  usually  has  a  "  smoky  "  appearance. 

(h.)  Microscope. — Collect  any  deposit  and  examine  it  microscop- 
ically for  blood-corpuscles,  which,  however,  are  frequently  dis- 
coloured or  misshapen. 

{c.)  Spectrum. — Examine  for  the  spectrum  of  oxy  haemoglobin 
or  met-hcemoglobin  (Lesson  YI.  6,  1). 

{(I.)  Guaiacum  Test. — Mix  some  freshly  prepared  tincture  of 
guaiacum  with  urine,  and  pour  on  it  some  ozonic  ether ;  a  blue 
colour  indicates  the  presence  of  haemoglobin.  This  reaction  may 
be  done  on  filter-paper. 

(<».)  Heller's  Blood  Test. — Make  the  urine  strongly  alkaline  with  caustic 
soda,  and  boil.  On  standing,  a  deJ)0^^.it  of  earthy  phosphates,  coloured  red  or 
brown  by  httmatin,  occurs,  the  dej)Osit  carrying  down  the  altered  colouring- 
matter  of  the  blood  with  it.     This  is  not  a  satisfactory  test. 

(/.)  The  urine  gives  the  reactions  of  albumin. 

2.  Haemoglobinuria. 

This  term  is  a]»])lied  to  that  condition  where  haemoglobin  is  excreted 
through  the  kidney  as  such,  and  is  not  contained  within  tlie  blood-corpuscles. 
Tlie  urine  contains  haemoglobin,  but  not  the  blood-corpuscles  as  such.  It 
occui-s  when  blood-corpuscles  are  destroyed  within  the  blood-vessels,  as  after 
the  transfusion  of  the  blood  of  one  s}>ecies  into  the  blood-vessels  of  another 
species  ;  after  the  transfusion  of  wann  water  :  the  injection  of  a  solution  of 
haemoglobin  into  a  vein  ;  and  after  extensive  destruction  of  the  skin  by  burn- 
ing. It  also  occurs  in  pur])ura,  scurvy,  often  in  typhus  or  scarlet  fever, 
pernicious  malaria,  in  "periodic  h;T?moglobinuria,"  and  after  the  inhalation 
of  arseniuretted  hydrogen. 

{(t.)  The  urine  gives  the  same  reactions  as  in  haematuria,  but  no 
blood -corpuscles  are  detected  by  the  microscope. 


xxil]  blood,  bile,  and  sugar  in  urine.  141 

3.  Bile  in  Urine. — The  biliary  constituents  appear  in  the  urine 
in  cases  of  jaundice  and  in  poisoning  with  phosphorus.  One  may 
test  for  the  bile-pigments,  or  the  hile-aci<U,  or  both. 

A.  Bile-Pigments. 

{a.)  Colour. — The  urine  has  usually  a  yellow  or  yellowish- green 
colour,  and  it  froths  very  easily  when  shaken.  Filter-paper  dipped 
into  it  gives  a  yellow  stain  on  drying. 

{h.)  Gmelin's  Test  (Nitric  acid  containing  Nitrous  acid). — (r.) 
Place  a  few  drops  of  the  suspected  urine  on  a  wliite  porcelain  plate, 
and  near  it  a  few  drops  of  the  impure  nitric  acid ;  let  the  fluids  run 
together  and  the  usual  play  of  colours  is  observed  (Lesson  XI.  6). 
(2.)  Take  urine  in  a  test-tube,  pour  in  the  imjiure  HXO3  until  it 
forms  a  stratum  at  the  bottom ;  if  bile-pigments  be  present,  at  the 
line  of  junction  of  the  fluids  a  play  of  colours  takes  place — from 
above  downwards — green,  blue,  violet  or  dirty  red,  and  yellow. 
Nearly  all  urines  give  a  play  of  colours,  but  (jreen  is  the  necessary 
and  characteristic  colour  to  prove  the  presence  of  bile-pigments. 
(3.)  Rosenbach's  Modification.— Filter  the  urine  several  times 
through  the  same  filter,  dry  the  filter-paper,  and  to  it  apply  tlie 
impure  nitric  acid,  when  the  same  play  of  colours  is  observed. 

(c.)  A  solution  of  methyl-violet  poured  on  icteric  urine  by  the  contact 
method  gives  a  bright  carmine  ring  at  the  point  of  contact. 

{d.)  If  much  bile-pigment  be  present,  the  following  test  succeeds  :— Mix 
the  urine  with  caustic  potash  ( i  KHO  to  3  water),  and  add  hydrochloric  acid. 
The  fluid  becomes  green,  due  to  the  formation  of  biliverdin. 

B.  Bile-Acids  (Glycocholic  and  Taurocholic  acids). 

(a.)  Pettenkofer's  Test.— Add  to  urine  a  few  drops  of  syrup  of 
cane-sugar  (8  per  cent.),  mix  them,  and  pour  strong  sulphuric  acid 
down  the  side  of  the  tube  until  it  forms  a  layer  at  the  bottom. 
The  temperature  must  not  rise  above  70''  C,  nor  must  the  urine 
contain  albumin.  At  the  line  of  junction  a  cherrij-red  or  purplc- 
viold  colour  indicates  the  presence  of  the  bile-acids.  Or  proceed 
as  follows  : — Shake  the  tube  with  the  urine  and  the  syrup  to  get  a 
froth,  and  when  the  sulphuric  acid  is  added  the  froth  shows  the 
colour.  N.B. — The  test  in  this  simple  form  often  fails  with  urine, 
and  in  fact  there  is  no  satisfactory  simple  test  for  minute  quantities 
of  these  acids  in  urine. 

(/).)  Strasburger's  Modification. — Dissolve  cane-sugar  in  the  suspected 
urine,  di])  into  it  filter-paper,  and  allow  this  to  dry.  Touch  tlie  i)a])cr  with  a 
glass  rod  dipped  in  strong  sulphuric  acid,  a  purple-violet  colour  indicates  the 
presence  of  the  bile-pigments. 

(c.)  Sulphur  Test.- Try  this  (Lesson  XI.  5). 

4.  Sugar  in  Urine  (Glycosuria). — Briicke  maintains  that  the 
merest  trace  of  glucose  or  grape-sugar  is  normally  present  in  urine. 


142  PRACTICAL  PHYSIOLOGY.  [XXIL 

In  diahfites  Jiielliius,  however,  it  occurs  in  considerable  amount,  and 
is,  of  course,  then  quite  abnormal. 

Characters  of  Diabetic  Ui-ine. 

(i.)  The  patient  usually  passes  a  very  large  quantity  of  urine, 
even  to  10,000  cc,  and  although  the  quantity  of  fluid  is  large 

(2.)  The  specific  gravity  is  high — 1030  to  1045 — due  to  the 
presence  of  the  grape-sugar.  iV^.^. — "When  the  quantity  of  urine 
is  above  normal,  and  the  specific  gravity  reaches  1030,  suspect  the 
presence  of  grape-sugar. 

(3.)  The  colour  is  usually  a  very  pale  straw,  from  the  dilution — 
not  diminution — of  the  mine  pigments.  The  urine  is  often  some- 
what turbid. 

(4,)  It  has  a  heavy  sweet  smelly  and  usually  froths  when  poured 
from  one  vessel  into  another. 

5.  Tests  for  Grape  Sugar.— In  all  cases  remove  any  albumin 
present,  e'.e.,  acidulate  with  acetic  acid,  boil,  and  filter. 

(a.)  Moore's  Test. — To  urine  add  an  equal  volume  of  caustic  soda  or  potash, 
and  boil  the  upper  stratum  of  the  fluid.  If  much  sugar  be  present,  a  dark 
sherry  or  bistre-brown  colour  is  obtained.  The  colour  may  vary  from  a  light 
yellow  to  a  dark  brown  (due  to  the  formation  of  glucic  and  melassic  acids), 
according  to  the  amount  of  sugar  present.     This  is  not  a  delicate  test. 

(6.)  Tronuner's  Test.— Add  to  the  urine  one-third  its  bulk  of 
caustic  soda  solution,  and  then  a  few  drops  of  a  solution  of  cupric 
sulphate,  and  a  clear  blue  solution  of  the  hydrated  oxide  is 
obtained.  Boil  the  ujjper  stratum  of  the  fluid.  If  sugar  be 
present,  a  yellow  or  yellowish-red  ring  of  reduced  cuprous  oxide 
is  obtained. 

(r.)  Fehling's  Solution  is  alkaline  potassio-tartrate  of  copper 
{l^^Cu2Qi^^0^.  Place  some  Fehling's  solution  in  a  test-tube  and 
boil  it.  If  no  discoloration  (yellow)  takes  place,  it  is  in  good  con- 
dition. Add  a  few  drops  of  the  suspected  urine  and  boil,  when 
the  mixture  suddenly  turns  to  an  opaque  yellow  or  red  colour, 
which  indicates  the  presence  of  a  reducing  sugar. 

{d.)  Bottger's  Test. — Mix  the  urine  with  an  equal  volume  of  sodium 
carbonate  solution,  add  a  little  basic  bismuth  nitrate,  and  boil  for  a  short 
time.     A  grey  or  black  deposit  indicates  the  presence  of  a  reducing  sugar. 

{c.)  Picric  Acid.— To  the  urine  add  an  equal  volume  of  a  saturated  watery 
solution  of  picric  acid,  and  then  caustic  potash.  Boil,  an  intensely  deep  red 
or  reddish-brown  colour  indicates  the  presence  of  a  reducing  sugar.  The 
larger  the  amount  of  sugar,  the  deeper  the  tint.  The  colouration  is  due  to 
the  formation  of  picramic  acid. 

(/.)  Phenyl-Hydrazin. — Repeat  this  as  described  in  Lesson  III. 
This  is  a  reliable  test. 


I 


XXIII.]  QUANTITATIVE   ESTIMATION   OF   SUGAR.  I43 

((J.)  Indigo-Camiine  Test,— To  the  urine  add  sodium  carbonate  solution  and 
indigo-carmine  solution  until  a  blue  colour  appears.  Boil,  and  a  yellow  colour 
is  obtained,  if  sugar  be  ])re3ent,  owing  to  the  reduction  of  indigo-blue  to  indigo- 
white.  Pour  the  fluid  into  a  cold  test-tube,  when  the  blue  colour  is  restored, 
a  beautiful  play  of  colours  intervening  between  the  yellow  and  the  blue.  This 
is  not  a  satisfactory  test. 

(k.)  Repeat  Molisch's  test  (Lesson  I.). 

6.  Preparation  of  Fehling's  Solution. — Solution  A.  34.64  grams  of  pure 
crystalline  cupric  sulphate  are  powdered  and  dissolved  in  500  cc.  of  distilled 
water.  Solution  B.  In  another  vessel  dissolve  173  grams  of  Rochelle  salts 
(sodio-potassium  tartrate)  in  100  cc.  of  i)ure  caustic  soda,  sp.  gr.  1.34,  and  add 
water  to  make  500  cc.  Keep  the  two  solutions  separate  in  stoppered  bottles, 
and  mix  them  as  required.  On  mixing  equal  quantities  of  A  and  B.  a  clear  deep 
blue  fluid  is  obtained,  the  Rochelle  salt  holding  the  cupric  hydrate  in  solution. 

N.B. — Fehling's  solution  ought  not  to  be  kept  too  long  ;  it  is  apt  to  decom- 
pose, and  should  therefore  be  kept  away  from  the  light,  or  protected  with 
opaque  paper  pasted  on  the  bottle.  Some  other  substances  in  urine — e.g.,  uric 
and  glycuronic  acids — reduce  cupric  oxide.  In  all  cases  see  thai  there  is  an 
excess  of  the  test  present. 


LESSON  XXIII. 
QUANTITATIVE  ESTIMATION  OP  SUGAR. 

1.  By  the  Saccharimeter. 

Study  the  use  of  some  form  of  saccharimeter.  The  portable  form  made  by 
Zeiss  is  very  convenient.  A  coloured  urine  must  first  be  decolorised  by  acetate 
of  lead  [Lesson  XX.  13  {d.)']. 

2.  Diabetic  Urine.  Volumetric  Analysis  by  Fehling's  Solution. 
— 10  cc.  of  Fehling's  solution  =  .05  gram  of  sugar. 

{a.)  Ascertain  the  quantity  passed  in  tAventy-four  hours. 

{h.)  Filter  the  urine,  and  remove  any  albumin  present  by  boiling 
and  filtration. 

{c.)  Dilute  10  cc.  of  Fehling's  solution  with  about  five  to  ten 
times  its  volume  of  distilled  water,  and  place  it  in  a  white  porcelain 
capsule  on  a  wire  gauze  support  under  a  burette.  [It  is  diluted 
because  any  change  of  colour  is  more  easily  ol:)served.] 

{(1.)  Take  5  cc.  of  the  diabetic  urine,  add  45  cc.  of  distilled 
water,  and  place  the  diluted  urine  in  a  burette.  Diabetic  urine 
usually  contains  4  p.c.  or  more  of  dextrose,  and  as  the  solution  to 
be  tested  should  not  contain  more  than  0.5  p.c.  of  dextrose,  hence 
the  necessity  for  diluting  the  urine. 

(e.)  Boil  the  diluted  FeliHng's  solution,  and  wliilst  it  is  boiling 
gradually  add  the  diluted  urine  from  the  burette  until  all  tlio 
cuprous  oxide  is  precipitated  as  a  reddish  powder,  and  tlie  super- 


144 


PRACTICAL   PHYSIOLOGY. 


[xxiit. 


natant  fluid  has  a  straw-yellow  colour,  not  a  trace  of  blue  remain- 
ing. This  is  best  seen  when  the  capsule  is  tilted.  It  is  not 
advisable  to  spend  too  much  time  in  determining  when  the  blue 
colour  disappears,  as  it  is  apt  to  return  on  cooling.  It  is  sometimes 
difficult  to  determine  when  all  the  blue  colour  has  disappeared. 
The  following  process  is  useful.  Filter  a  little 
of  the  hot  fluid,  acidulate  with  acetic  acid  and 
add  potassic  ferrocj^anide.  If  copper  is  present 
a  brown  colour  or  precipitation  is  produced.  If 
this  be  so,  add  more  urine  until  no  brown  colour 
is  produced. 

[Pavy's  modification  of  Fehling's  solution  is  sometimes 
used.  In  it  ammonia  holds  the  cojjper  in  solution,  so 
that  there  is  no  yellow  or  red  precipitate  formed,  as  tlie 
ammonia  holds  the  oxide  in  solution.  The  reduction 
is  com})lete  when  the  blue  colour  disa})})ears.  lo  cc. 
Pavy's  Fehling=i  cc.  rehling  =  5  milligrams  of  dex- 
trose.] 

(/.)  Read  ofl"  the  number  of  cc.  of  dihde 
urine  employed.  If  i8  cc.  were  used,  this,  of 
course,  would  represent  1.8  cc.  of  the  original 
urine. 

(g.)  Make  a  second  determination,  using  the 
data  of  the  first,  and  in  this  case  run  in  at  once 
a  little  less  of  the  dilute  urine  than  was  reqidred 
at  first. 

Example.— Suppose  the  patient  passes  8550 
cc.  of  urine,  then  as  1.8  cc.  of  urine  reduced  all 
the  cupric  oxide  in  the  10  cc.  of  Fehling's  solu- 
tion, it  must  contain  0.5  gram  sugar;  hence 

1.8  :  8550  :  :  .05.*.  -^^—5 — ?  =  237.5  grants  of 

I.o 

Fio.  72.— Ficro-Sac- 

chariiiieter.  sugar  passed  in  twenty -four  hours, 

3.  Picro-Sacchariineter  of  G.  Jolinson. 

Solutions  Eequired. 

(i.)  A  solution  of  ferric  acetate  the  colour  of  which  is  equal  to  that  yielded 
Dy  a  solution  of  sugar  containing  ^  grain  per  tluid  ounce. 

(2.)  Saturated  solution  of  picric  acid. 

(3.)  Liquor  potassa;  (B.P.). 

{a.)  Measure  i  fluid  drachm  of  urine  into  the  boiling  tube,  add  30  minims 
of  liquor  potassae  and  80  minims  of  the  saturated  solution  of  picric  acid. 
Make  up  to  the  4-drachm  mark  on  tlie  tube  with  distilled  water.  Boil  for 
one  minute. 


XXIII.] 


QUANTITATIVE   ESTIMATION   OF  SUGAR 


145 


(b.)  Dip  the  tube  in  cold  water  to  cool  it.  The  volume  must  be  exactly  4 
drachms.  If  it  is  less,  add  water  ;  if  more,  evaporate  it.  If  the  colour  of  the 
boiled  liquid  is  tlie  same  as  that  of  the  ferric  acetate  :J-grain  standard,  or 
paler,  the  urine  contains  i  grain  of  sugar  per  Huid  ounce,  or  less. 

(c.)  Should  the  colour  be  darker  than  the  standard,  place  some  of  the  boiled 
liquid  in  the  graduated  stoppered  tube  (fig.  72)  to  fill  ten  divisions  of  the 
scale,  while  the  stoppered  tube  afiixed  to  the  former  is  filled  with  the  SS.  of 
ferric  acetate.  Fill  up  the  graduated  tube  with  distilled  water  until  the  dark 
red  liquid  has  the  same  colour  as  that  of  the  SS.  These  tints  are  best  compared 
in  the  flat-bottomed  tubes  supplied  with  the  apparatus. 

(d.)  Read  off  the  level  of  the  fluid  in  the  saccharimeter,  each  division 
above  10  =  0.1  grain  per  fluid  oz.     Thus,  13  divisions  =  .3  grains  per  fluid  oz. 

(e.)  If  more  than  8  grains  per  oz.  are  present,  further  dilution  is  required. 
Full  instructions  are  supplied  with  the  apparatus. 


4.  Fermentation  Method. — Sir  William  Roberts  has  devised  a  method 
depending  on  the  diminution  of  the  specific  gravity  which  the  fluid  undergoes 
during  fermentation.  Every  degree  lost  in  the  sp.  gr.  corresponds  to  i 
grain  of  sugar  in  a  fluid  ounce.  Recently  a  modification  of  this  method  has 
been  introduced  in  Germany  under  the  title  of  Einhorn's  Fermentation 
Saccharometer  (fig.  73).  Estimate  the  specific  gravity  of  the  urine,  which  ia 
diluted  according  to  the  specific  gravity  as  follows.     If  the  urine  have  a 

Sp.  gr.  loi 8-1022,  dilute  it  with  2  vols,  water, 
II      1022-1028,        „        „     5    „ 
„      1028-1038,        „        „    10    „        „ 

Measure  10  cc.  of  the  urine,  and,  by  means  of  a  pipette,  place  it  in  the  appa- 
ratus. Add  I  gram  of  yeast  to  the  urine  in  the  tube,  incline  the  latter  until 
the  fluid  flows  into  the  limb  of  the  latter.  Let 
the  apparatus  stand  at  the  ordinary  temperature 
for  fifteen  hours,  and  then  the  quantity  of  CO2 
given  off  is  read  off".  The  scale  on  the  tube  is 
empirical,  and  indicates  directly  the  percentage  of 
sugar  in  the  urine.  1^ 

6.  Acme  Sacchar-Ureameter  (fig.  74).— This  is 
a  simple  apparatus  for  the  direct  estimation  of  sugar 
and  urea  in  urine  ;  the  former  by  the  fermentation 
test,  the  latter  by  the  hypobromite. 

Estimation  of  Sugar. —Measure  i  volume  of  the 
urine  in  the  tube  so  marked,  and  i)our  it  into  the 
bottle  a.  Wash  out  with  water,  and  add  to  the 
urine.  Dilute  further  with  water  if  the  urine 
contains  much  sugar.  Acidify  the  urine  with 
tartaric  acid  until  acid  to  test-paper  (^-i  per  cent. 
of  free  acid).  Add  a  few  grains  of  yeast,  and 
connect  up  the  apparatus.  The  measuring-tube  b 
is  filled  to  zero  with  a  saturated  solution  of  common 
salt  (the  COj  is  soluble  in  water).  When  b  is 
full,   c  must  bo  empty.      Place  the  whole  in  a 

moderately  warm  place — the  surrounding  temperature  should  be  such  as  to 
enable  it  to  rise  to  92°-94°  F.  When  the  fermentation  ceases — or  frofn  time 
to  time  during  the  time  of  fermentation — lower  c  until  the  levels  of  bjine  are 
equal.     Allow  it  to  cool,  and  read  off"  the  result. 


Fia.  73. — Einhorn's  Farmen- 
tation  Saccharoniiter. 


146 


PRACTICAL  PHYSIOLOGY. 


[xxin 


6.  Aceto- Acetic  Acid  is  found  in  certain  diabetic  urines,  but  not  in  all. 

(a.)  To  the  urine  add  ferric  chloride ;  a  red  colour  is  obtained  if  this  acid 

be  present.  If  there  is  a 
deposit  of  phosphates,  filter. 
The  colour  disappears  on 
heating. 

If  a  diabetic  urine  con- 
taining aceto-acetic  acid  be 
distilled,  this  acid  is  de- 
composed, and  aceton  is 
obtained. 

7.  Tests  for  Aceton 
(CsHgO).— To  obtain  the 
aceton,  acidulate  half  a 
litre  of  urine  with  HCl. 
The  distillate  will  give  the 
following  reactions : — 

(a.)  Lieben's  Test.— To 
a  weak,  watery  solution  of 
aceton  add  solution  of  iodine 
dissolved  with  the  aid  of 
potassic  iodide,  and  then 
caustic  soda.  A  yellow 
precipitate  of  iodoform  is 
obtained.  The  precipitate 
is  generally  described  as 
forming  hexagonal  plates  or 
radiate  stars,  but  I  have 
generally  found  it  to  be 
amorphous  or  granular. 
Other  substances  give  the 
iodoform  reaction. 

(b.)  Smell  the  peculiar 
ethereal  odour  of  aceton. 

(c.)  Legal's  Test.— Add 
caustic  soda  solution,  and 
then  a  solution  of  freshly- 
prepared  sodium  nitro- 
^g  prusside  and  acetic  acid  =  a 
red  colour. 

In  all  cases  employ  both 
tests,  but  they  only  give  a 
decided  reaction  in  urine 
when  the  aceton  is  in  con- 
siderable amount.  To  be 
quite  certain  that  aceton  is  present,  a  considerable  amount  of  the  urine 
must  be  distilled,  and  the  tests  applied  to  the  distillate. 

8.  Tests  for  PhenoL  — The  method  of  obtaining  phenol  from  its  compound 
in  the  urine  is  given  at  p.  134,     To  a  watery  solution  of  phenol — 

(a.)  Add  ferric- chloride  =  a  bluish- violet  colour. 

{h.)  Add  bromine  water  =  a  yellow  (or  rather  white}  precipitate  of  bromine 
compounds. 

(c.)  Add  Millon's  reagent -a  beautiful  red  colour  or  deposit.  This  reactior 
is  aided  by  heat 


Fig.  74.— Sacchar-Ureameter,  made  by  Messrs.  Gibbs, 
Cuxson  &  Co.,  Wednesbury. 


XXIV.]  URINARY   DEPOSITS,  ETC.  1 47 

9.  Pyrocatechin  is  sometimes  found  in  urine.  The  method  of  obtaining  it 
requires  too  much  time  to  be  done  in  this  course. 

Tests. 

(a.)  To  a  dilute  solution  add  ferric  chloride  =  a  green  colour,  which  becomes 
violet  on  the  addition  of  sodic  bicarbonate. 

(b.)  Add  ammonia  and  silver  nitrate,  which  give  a  black  precipitate  of 
reduced  silver. 


LESSON  xxrv. 

URINARY  DEPOSITS— CALCULI  AND  GENERAL 
EXAMINATION  OF  THE  URINE. 

1.  Mode  of  Collecting  Urinary  Deposits. — (i.)  Place  the  urine  in 
a  conical  glass,  cover  it,  and  allow  it  to  stand  for  twelve  hours. 
Note  the  reaction  before  and  after  standing.  With  a  pipette 
remove  some  of  the  deposit  and  examine  it  microscopically. 

(ii.)  Dr.  Harris  has  published  the  following  (Brit.  Med.  Jour.^ 
1894,  vol.  i.  p.  1356) : — The  urine  is  placed  in  a  tube  drawn  to  a 
fine  point,  and  fixed  in  a  vertical  position  in  a  clamp.  The  pointed 
end  is  down,  and  after  being  filled  it  is  corked  tight.  After  the 
deposit  subsides  and  collects  in  the  lower  pointed  end  of  the  tube, 
a  small  quantity  of  it  may  be  obtained  by  clasping  the  tube  with 
the  warm  hand  or  by  pushing  in  the  cork  slightly. 

(iii.)  Centrifuge. — By  means  of  a  small  hand  centrifuge  (fig.  75, 
reduced  to  i),  as  made  by  Muencke  of  Berlin,  any  deposit  in  urine 
is  readily  collected  at  the  bottom  of  a  test-tube.  The  disc  I,  bear- 
ing the  tubes  G,  can  be  made  to  rotate  3000  to  5000  times  per 
m'inute.  Fig.  II.  shows  the  disc  in  full  rotation,  and  III.  the  form 
of  glass  vessel  used. 

There  are  two  classes  of  deposits,  organised  and  unorganised. 

ORGANISED  DEPOSITS. 


1.  Pus  (p.  147). 

2.  Blood  (p.  140). 

3.  Epithelium. 

4.  Renal  tube  casts. 


5.  Spermatozoa. 

6.  Micro-organisms. 

7.  Elements  of  morbid  growths 

and  entozoa. 


2.  Pus  in  Urine  (Pyuria)  produces  a  thick  creamy  yellowish-white  sedi- 
ment after  standing,  although  its  aj)i)earance  varies  witli  the  reaction  of  the 
urine.  If  the  urine  be  arld^  tlie  ])vecipitate  is  loose,  and  the  ])us-cori)Usclcs 
discrete  ;  if  alkaline,  and  especially  from  ammonia,  it  forms  a  tliick.  tongh, 
glairy  mass.  The  urine  is  usually  alkaline,  and  is  always  albuminous,  and 
rapidly  undergoes  decomi)Osition.  Pus  is  found  in  the  urine  in  Ieucorrh<ia 
in  the  female,  gonorrha-a,  gleet,  cystitis,  pyelitis,  from  bursting  of  an  abscess 
into  any  part  of  the  urinary  tract,  &c. 


I4S 


PRACTICAL   PHYSIOLOGY. 


[XXIV. 


{a.)  Donne's  Test. — Filter  off  the  fluid,  and  add  to  the  deposit  a  small 
piece  of  caustic  jiotash,  or  a  few  drops  of  strong  solution  of  caustic  potash  ; 
the  deposit  becomes  ropy  and  gelatinous,  and  cannot  be  dropped  from  one 
vessel  into  another — due  to  the  formation  of  alkali-albumin  ;  the  deposit  is 
pus.  Tlie  same  reagent  with  mucus  causes  the  deposit  to  become  more  fluid 
and  limpid,  to  clear  up,  and  look  like  unboiled  white  of  egg. 


Fig.  7S. 


-Hand  Centrifage  made  by  Muencke,  Luisen  Strasse,  58,  Berlin,  N.W. 
Cost,  ;^3,  10/. 


{h.)  With  the  microscope  numerous  pus-corpuscles  are  seen,  which,  when 
acted  on  by  acetic  acid,  show  a  bi-  or  tri-partite  nucleus.  This  test  is  not 
absolutely  conclusive. 

(f.)  Urine  containing  pus  gives  the  reactions  for  albumin,  while,  if  mucus 
alone  be  present,  it  gives  only  those  for  mucin. 


XXIV.l 


URINARY   DEPOSITS,   ETC. 


149 


UNORGANISED    DEPOSITS. 


A.  In  Acid  Urine. 

1.  Amorphous. 

{a. )  Urates.  — Soluble  when  heated, 
redeposited  in  the  cold  ;  when  hydro- 
chloric acid  is  added  microscopic  crys- 
tals of  uric  acid  are  formed  =  urates. 

{b.)  Tribasic  Phosphate  of  Lime. 
— Not  dissolved  by  heat,  but  disap- 
pears without  effervescence  on  adding 
acetic  acid.  It  is  probably  tribasic 
phosphate  of  lime  (CagaPOj. 

(c. )  Oil  Globules.  —  Very  small 
highly  refractive  globules,  soluble  in 
ether  (very  rare). 

2.  Crystalline. 

(a.)  Uric  Acid. — Recognised  by  the 
shape  and  colour  of  the  crystals  and 
their  solubility  in  KHO. 

(b.)  Oxalate  of  Lime. — Octahedral 
crystals,  insoluble  in  acetic  acid  (fig. 
76). 

(c.)  Cystin(  very  rare). — Hexagonal 
crystals,  soluble  in  NH^HO  (fig.  78). 


(d.)  Leucin  and  Tyrosin  (very 
rare).     (Fig.  79.) 

(e.)  Gholesterin  (very  rare).  (Fig. 
40.) 

3.  Urinary  Calculi. 


B.  In  Alkaline  Urine. 
I.  Amorphous, 
(a.)  Tribasic  Phosphate  of  Lime 
dissolves  in  acids  without  efferves- 
cence. 


{b.)  Carbonate  of  Lime. 
below.) 


(See  (f.) 


2.   Crystalline. 

{a.)  Triple  Phosphate. — Shape  ol 
the  crystals  (knife-rest  or  coffin-lid), 
soluble  in  acids. 

(b.)  Acid  Ammonium  Urate.  — 
Small  dark  balls,  often  covered  with 
spines,  and  also  amorphous  granules 
(%  77). 

(c.)  Carbonate  of  Lime. — Small 
colourless  balls,  often  joined  to  each 
other  ;  ell'ervescence  on  adding  acids 
(microscope). 

{(l.)  Crystalline  Phosphate  of 
L^me. 

(e. )  Lencin  and  Tyrosin  (very  rare). 

(Fig.  79') 


They  are  composed  of  urinary  constituents  which  form  urinary  deposits, 
and  may  consist  of  one  substance  or  of  several,  which  are  usually  deposited  in 


0 

♦ 


* 


♦ 


Fio.  76.— Oxalate  of  Lime.    Octa- 
hedra  and  Hour-glass  forms. 


mm 

Fio.  77.— Acid  Urate  of  Ammonium. 


layers,  in  which  case  the  most  central  part  is  spoken  of  as  the  '*  nucleus.** 
The  nucleus  not  unftequently  consists  of  some  colloid  substance— mucus,  a 


ISO 


PRACTICAL  PHYSIOLOGY. 


[XXIV 


© 


0 
0 


0 


<:^ 


ii^ 


portion  of  blood-clot,  or  some  albuminoid  matter— in  which  crystals  of  oxalate 
of  lime  or  globular  urates  become  entangled.     Layer  after  layer  is  then  de- 
posited.    In  certain  cases  the  nucleus  may  con- 
y"--,^^  /—^  sist  of  a  foreign  body  introduced  from  without. 

^^-V^  \  >Sr  Calculi  are  sometimes  classified  as  jirimanj  and 

^^^  ^^  secondary ;  the  former  are  due  to  some  general 

alteration  in  the  composition  of  the  urine,  whilst 
the  latter  are  due  to  ammoniacal  decom])Osition 
of  the  urine,  resulting  in  the  precipitation  of 
Q  phosphates  on  stones  already  formed.  This  of 
course  has  an  important  bearing  on  the  treat- 
ment of  calculous  disorders.  Calculi  occur  in 
acid  and  alkaline  urine.  A  higldy  acid  urine 
favours  the  formation  of  t/ric  ac?rf  calculi,  because 
that  substance  is  most  insoluble  in  very  acid 
urine.  A  highly  alkaline  urine  favours  the  for- 
mation of  calculi  consisting  of  calcium  phosphate  or  triple  phosphate,  as  these 
substances  are  insoluble  in  alkaline  urine. 


Fig.  78.— Cystin. 


4.  Method  of  Examining  a  Calculus 

(a.)  Make  a  section  in  order  to  see  if  it  consists  of  one  or  more 
substances ;  examine  it  with  the  naked  eye,  and  a  portion  micro- 
scopically. 

(b.)  Scrape  off  a  little,  and  heat  it  to  redness  on  platinum  foil 
over  a  Bunsen-burner. 


FiO.  79. — a.a.  Leucln  balls  ;  b.b.  Tyrosln  sheaves  ;  e.  Doable  balls  of 

ammonium  mate. 

(A.)  If  it  be  entirely  combustible^  or  almost  so,  it  may  consist  of 
uric  acid  or  urate  of  ammonium,  xanthin,  cystin,  coagulated  fibrin 
or  blood,  or  ureosteahth. 


XXIV.]  URINARY   DEPOSITS,  ETC.  I5I 

(B.)  Tf  mcomlncifilJe,  or  if  it  leaves  much  ashj  it  may  consist  of 
urates  with  a  fixed  base  (Na,  Mg,  Ca),  oxalate,  carbonate,  or 
phosphate  of  lime,  or  triple  phosphate. 

5.  A.  Combustibl^.— Of  tliis  group,  uric  acid  and  urate  of 
ammonium  give  the  nnirt'xide  test. 

(i.)  Uric  Acid  is  by  far  the  most  common  form,  and  constitutes 
five-sixths  of  all  renal  concretions.  Concretions  the  size  of  a 
split-pea,  or  smaller,  may  be  discharged  as  (/ravel.  "When  retained 
in  the  bladder,  they  are  usually  spheroidal,  elliptical,  and  some- 
what flattened;  are  tolerably  hard;  the  surface  may  be  smooth 
or  studded  with  fine  tubercules;  the  colour  may  be  yellowish, 
reddish,  reddish  brown,  or  very  nearly  white.  When  cut  and 
polished,  they  usually  exhibit  a  concentric  arrangement  of  layers. 
Not  unfrequently  a  uric  acid  calculus  is  covered  with  a  layer  of 
phosphates,  and  some  calculi  consist  of  alternate  layers  of  uric 
acid  and  oxalate  of  lime.  Its  chemical  relatio7is  :  nearly  insoluble 
in  boiling  water;  soluble  in  KHO,  from  which  acetic  acid  preci- 
pitates uric  acid  crystals  (microscopic) ;  gives  the  murexide  test 
(Lesson  XX.  3). 

(ii.)  Urate  of  Ammonium  Calculi  are  very  rare,  and  occur 
chiefly  in  the  kidneys  of  children ;  they  form  small  irregular,  soft, 
fawn-coloured  masses,  easily  sohible  in  hot  water. 

(iii.)  If  the  calculus  is  combustible  and  gives  no  murexide  test, 
it  may  consist  of  xanthin,  which  is  very  rare,  and  of  no  practical 
importance. 

(iv.)  Cystin  is  very  rare,  has  a  smooth  surface,  dull  yellow 
colour,  which  becomes  greenish  on  exposure  to  the  air;  and  a 
glistening  fracture  with  a  peculiar  soapy  feeling  to  the  fingers ; 
soft,  and  can  be  scratched  with  the  nail.  It  occurs  sometimes  in 
several  members  of  the  same  family.  It  is  soluble  in  ammonia 
and  after  evaporation  it  forms  regular  microscopic  hexagonal 
plates  (fig.  78). 

The  other  calculi  of  this  group  are  very  rare. 

6.  (A.)  Group. — Apply  the  Murexide  Test. 

It  is     /  Treat  the  original  powder  with  \  No  odour         =  Uric  acid. 
obtained  \  potash.  J  Odour  of  NH3  ==  Ammonium  uraU, 

The  residue  is  not  coloured,  but  becomes  yellowish-red  \^  =  Xanthin. 

on  adding  caustic  potash        .....  j 
The  residue  is  not  coloured  either  by  KHO  or  NH4HO  ;  ) 

the  original  substance  is  soluble  in  ammonia,  and  ^  '^Cystin, 

on  evaporation  yields  hexagonal  crystals        .         .  ) 
On  heating,  it  gives  an  odoui'  of  burned  feathers  ;  the  "j 

substance  is  soluble  in  KHO,  and  is  precipitated  V-'Proteid, 

therefrom  by  excess  of  HNO3  •        •        .         >  j 


152  PRACTICAL   PHYSIOLOGY.  [XXIV. 

7.  B.  Incombustible. 

(i.)  Urates  (Na,  Ca,  Mg),  are  rarely  met  with  as  the  sole  con- 
stituent.    They  give  the  murexide  test. 

(ii.)  Oxalate  of  Lime  or  mulberry  calculi,  so  called  because 
their  surface  is  usually  tuberculated  or  warty;  they  are  hard, 
(lark-brown,  or  black.  These  calcuU,  from  their  shape,  cause 
great  irritation  of  the  urinary  mucous  membrane.  When  in  the 
form  of  gravel,  the  concretions  are  usually  smooth,  variable  in 
size,  pale-grey  in  colour.  Layers  of  oxalate  of  lime  frequently 
alternate  with  uric  acid.  When  heated  it  blackens,  but  does  not 
fuse,  and  then  becomes  white,  being  converted  into  the  carbonate 
and  oxide.  The  white  mass  is  alkaUne  to  test-paper,  and  when 
treated  with  HCl,  it  effervesces  (COg).  Oxalate  of  hme  is  not 
dissolved  by  acetic  acid. 

(iii.)  Carbonate  of  Lime. — Rare  in  man;  when  met  with,  they 
usually  occur  in  large  numbers.  Dissolve  with  effervescence  in 
HCl.  Sometimes  crystals  occur  as  a  deposit.  They  are  common 
in  the  horse's  urine. 

(iv.)  Basic  Phosphate  of  Lime  Calculi  are  very  rare,  and  are 
white  and  chalky. 

(v.)  Mixed  Phosphates  (Fusible  Calculus)  consist  of  triple- 
phosphate  and  basic  phosphate  of  lime.  They  indicate  that  the 
urine  has  been  ammoniacal  for  some  time,  owing  to  decomposi- 
tion of  the  urea.  They  are  usually  of  considerable  size,  and 
whitish ;  the  consistence  varies.  When  triple-phosphate  is  most 
abundant,  they  are  soft  and  porous,  but  when  the  phosphate  of 
lime  is  in  excess,  they  are  harder.  A  vJiitish  deposit  of  phos- 
phates is  frequently  found  coating  other  calculi.  This  occurs 
when  the  urine  becomes  ammoniacal,  hence  in  such  cases  regard 
must  ahvays  be  had  to  the  condition  of  the  urinary  mucous 
membrane.  Such  calculi  are  incombustible,  but,  when  exposed  to 
a  strong  heat,  fuse  into  a  white  enamel-like  mass,  hence  the  name, 
fusible  calcuH. 

8.  (B.)  Group. 

(i.)  The  substance  gives  the  murexide  reaction^  indicates  urates. 

The  residue  is  treated  with  water. 

It  is  soluble,  and  (  Neutralise  ;  add  platinic  chloride,  a  yel-  \  ^  Potastium. 

the   solution   is  ^      low  precipitate /~ 

alkaline    ,         .  (  The  residue  yields  a  yellow  flame  .     =  Sodium, 

(  Ammonium  oxalate  gives  a  white  crys-  j  _  Caldum. 

Scarcely    soluble ;  |      talline  precii)itate      .         .         .         .  /  ~  * 

the    solution   is  |  Ammonium  oxalate  gives  no  precipitate, " 
scarcely      alka- 1      but  on  adding  ammonium  chloride, 
line  ;  soluble  in  i      sodic  phosphate,  and  ammonia,  there  )■=' Magnesium, 
acetic  acid         .  |      is  a  crystalline  precipitate  of  triple- 
L     phosphate  .... 


XXIV.]  URINARY   DEPOSITS,  ETC.  1 53 

(ii.)  The  original  substance  does  not  give  the  murexide  test. 

Treat  the  original  substance  with  hydrochloric  acid. 

T.  J.      1  ..1.    «.  f  Calcium  carbonate. 

It  dissolves  with  effervescence        ....       -  \  Magnesium  crtrb. 

T.      J.      1        r  It  dissolves  with  effervescence        .         .      =  Calcium  oxalate. 
It      dissolves 

without  ef- 
fe  rvoscence. 
Heat  the 
original  sub- 
stance, and 
treat  it  with 
HCl     . 


( It      melts.  \  -CI  „  -  1  _  o  o  ^ 
j    The  origi-        ^H  I  ^  Triple pJwsphate. 

There  is  no  |    "^^  /J°"^  [e  v  o  iVe  s  nil  ^  ..,       .      ,^ 


nal    stone  >t:i       i  < 

4.  ,-.|Evolve3no|       ^t-*      /      i 

effervs'ce  j     t  r  e  a  t  e  d         j. „  V=Neut.  calc. y>hos'p. 

Heat  in  a'    ^ithKHOJ      ^^^'         'i 
Meatm  a     j^  does  not  ^ 

m  e  1 1  o  n  [-     .        •        .     —  Acid  calc.  pfwsp. 
heating    .  j 


capsule 


9.  General  Examination  of  the  Urine. 

(i.)  Quantity  in  twenty-four  hours  (normal  50  oz,,  or  1500  cc). 

(ii.)  Colour,  Odour,  and  Transparency  (if  bile  or  blood  be  sus- 
pected, test  for  them). 

(iii.)  Specific  Gravity  of  the  mixed  urine  (if  above  1030,  test  for 
sugar). 

(iv.)  Reaction  (normally  slightly  acid ;  if  alkaline,  is  the  allcali 
volatile  or  fixed  1). 

(v.)  Heat. 

(a.)  If  a  turbid  urine  becomes  clear  =  urates. 

(h.)  If  it  becomes  turbid  =  earthy  ])hosphates  or  (dhnmin. 
Albumin  is  precipitated  before  the  boiling-point  is  reached  (73° 
C),  whilst  phosphates  are  thrown  down  about  the  boiling-point. 
It  is  necessary,  however,  to  add  HNO3,  which  will  dissolve  the 
phosphates,  but  not  the  albumin.  A  case  may  occur  where  both 
urates  and  albumin  are  present ;  on  carefully  heating,  the  urine 
will  first  become  clear  (urates),  and  then  turbid,  Miiich  turbidity 
will  not  disappear  on  adding  HNO3  (albumin).  Estimate  approxi- 
mately the  amount  of  albumin  present. 

(vi.)  Test  for  Chlorides,  with  HNO3  and  AgN03  (if  albumin  be 
present,  it  must  be  removed  by  boiling  and  filtration). 

(vii.)  If  sugar  be  suspected,  test  for  sugar  (Moore's,  Trommer's, 
or  Fehling's  test),  and  if  albumin  be  present,  remove  it. 

(viii.)  Make  naked-eye,  microscopic,  and  chemical  examinations 
of  the  sediment. 


154  PRACTICAL   PHYSIOLOGY.  [XXIV. 


APPENDIX. 

Exercises  on  the  Foregoing. 

A.  The  student  must  practise  the  analysis  of  fluids  containing 
one  or  more  of  tlie  substances  referred  to  in  tlie  foregoing 
Lessons. 

No  hard  and  fast  rule  can  be  laid  down  for  the  examination  of 
the  fluids  met  with  in  physiological  work  at  all  comparable  with  the 
method  employed  in  inorganic  chemistry.  To  begin  with,  the 
student  must  be  largely  guided  by  the  physical  characters, — colour, 
smell,  taste,  etc. — of  the  fluid  he  is  dealing  with,  and  these  will 
usually  give  him  a  satisfactory  clue  as  to  the  chemical  tests  he 
should  employ. 

N.B. — In  all  cases  concentrate  some  of  the  fluid  for  subsequent 
use  if  required,  and  complete  the  concentration  on  a  water-bath  to 
avoid  overheating  or  charring. 

A  colourless  solution  should  be  examined  for  proteids  and  carbo- 
hydrates by  the  method  described  in  Lesson  lY.,  p.  32.  Marked 
opalescence  will  indicate  milk  or  glycogen,  less  distinct  opalescence 
may  suggest  the  presence  of  starch  or  certain  proteids.  Colourless 
solutions  may  also  contain  urea,  bile-salts,  leucin,  tyrosin  or  fer- 
ments. 

Colour: — A  red  colour  will  suggest  blood,  a  green  tint  bile,  a 
yelloio  urine,  a  brown  methcemoglobin  or  haematin.  If  blood- 
pigment  or  one  of  its  derivatives  is  suspected,  use  the  spectroscope 
at  once,  and  observe  the  spectrum  of  (a)  the  original  solution,  (b) 
the  same  shaken  with  air,  and  (c)  after  the  addition  of  (NH^)2S. 

The  smell  may  give  an  indication  as  to  the  presence  of  bile  or 
urine.     Do  chemical  tests  accordingly. 

Taste : — If  salt,  examine  for  globulins  or  urea,  if  bitter  for  bile- 
salts,  if  siveef  for  sugars. 

Following  the  indications  obtained  from  the  physical  characters, 
select  from  the  following  chemical  tests  those  applicable  to  the 
fluid  which  is  being  examined. 

1.  Test  for  proteids  by  xanthoproteic  and  Millon's  tests,  and  for 
carbohydrates  by  iodine  and  Trommer's  test.  The  tests  for  special 
proteids  and  carbohydrates  have  been  already  described  (p.  32). 

2.  Blood  : — Test  chemically  for  proteid  constituents. 

3.  Bile: — Do  Gmelin's  test  for  bile-pigments,  and,  if  proteids 
are  absent,  Pettenkofer's  test  for  bile-acids.  If  proteids  (not  pro- 
teoses and  peptones)  are  present,  neutrahse,  boil,  filter,  and  test 
filtrate  for  bile-salts.  Remove  proteoses  and  peptones,  if  present, 
by  precipitation  with  alcohol,  filter  and  test  filtrate  for  bile-salts. 


XXIV.]  URINARY   DEPOSITS,  ETC.  1 55 

4.  Tyrodn ; — Add  million's  reagent  and  boil.  A  red  colour  in 
the  solution  indicates  the  presence  of  tyrosin. 

5.  Urea: — (i.)  Add  sodium  hypobromite  or  impure  nitric  acid 
(containing  HNO2).  If  no  bubbles  of  gas,  no  urea  is  present.  If 
gas  given  off  (2.)  remove  phosphates  and  sulphates  by  addition  of 
baryta  mixture  and  filtration,  and  remove  proteids  (see  3.),  concen- 
trate the  filtrate  if  necessary,  place  a  drop  on  each  of  two  slides, 
allow  one  to  evaporate  slowly  under  a  cover-glass,  and  to  the  otlier 
add  a  drop  of  strong  pure  HNO3  and  cover.  J^xamine  the  former 
for  crystals  of  urea,  and  the  latter  for  crystals  of  urea  nitrate.  For 
other  tests  see  Lesson  XVIII.,  p.  119). 

6.  Uric  arid : — If  in  solution,  is  in  the  condition  of  a  urate, 
(i.)  Add  a  drop  of  HCl  and  allow  to  stand  for  24  hours.  Examine 
deposit  for  crystals  of  uric  acid.  (2.)  Concentrate  original  solution 
(after  removal  of  any  proteids  present),  and  apply  the  murexide 
test  to  a  small  quantity. 

7.  Kveatinin : — Add  a  drop  of  dilute  solution  of  nitroprusside 
of  sodium  and  excess  of  caustic  soda.  A  burgundy-red  colour 
indicates  kreatinin. 

8.  Ferments  : — {a.)  Digestive  ferments. — Place  5  cc.  of  the  sus- 
pected fluid  in  each  of  four  test-tubes.  Label  these  A,  B,  C,  and  D. 
Neutralise  the  fluid  in  C  and  D,  if  necessary.  To  A  add  5  cc. 
.4  per  cent.  HCl  and  a  thread  of  boiled  fibrin,  to  B  5  cc.  of  2  per 
cent,  sodium  carbonate  solution  and  a  thread  of  boiled  fibrin,  to  C 
5  cc.  starch  solution,  and  to  D  5  or  10  cc.  milk.  Place  the  four 
tubes,  along  with  four  control  tubes  A',  B',  C,  L)'  (the  contents  of 
which  are  the  same  as  those  of  A,  B,  C,  and  D,  but  without  the 
suspected  solution)  on  a  water-bath  at  40°  C.  After  a  time  (10  to 
30  mins.)  examine  the  tubes.  Digestion  in  A,  B,  or  C,  or  coagula- 
tion of  the  milk  in  D,  indicates,  if  there  is  no  corresponding  change 
in  the  control  tube,  the  presence  of  pepsin ^  trypsin,  amylolytic 
ferment  or  rennin  respectively. 

{!>.)  Blood  ferment. — ^If  the  solution  is  suspected  to  be  salted 
plasma,  or  if  it  be  oxalate  plasma,  in  the  former  case  dilute  with 
water  and  place  in  a  water-bath.  (Lesson  V.  21.)  In  the  latter 
add  calcium  chloride  (Lesson  V.  14),  and  observe  if  coagulation 
occurs.     This  will  also  show  presence  of  fibrinogen. 

N.B. — In  all  cases  make  a  note  of  what  you  do,  the  result 
thereof,  and  your  inferences.    The  following  form  is  convenient : — 

Expenment,        \        Observation        \        Inference, 


156  PRACTICAL   PHYSIOLOGY.  [XXIV. 

B.  Examination  of  Solid  substances. 
Physical  characters. 

1.  Tho.  colour  may  suggest  blood-pigment,  or  one  of  its  deriva- 
tives, or  bile-pigment. 

2.  Taste  may  indicate  bile-salts,  urea,  or  sugar. 

3.  Examine  microscopically  to  see  whether  amorphous  or 
crystalline.  If  the  latter,  the  substance  may  be  recognised  by  its 
crystalline  form,  e.g.,  urea,  uric  acid,  urates,  leucin,  tyrosin,  choles- 
terin,  &c. 

4.  Burn  some  in  a  tube ;  smell  it  to  detect  any  odour.  Observe 
if  it  leaves  an  ash. 

5.  Examine  its  solubility  in  cold  and  warm  water,  caustic  soda, 
dilute  acid,  saline  solutions,  alcohol  and  ether.  Test  the  solution 
in  the  first  four  reagents  as  directed  under  examination  of  fluids. 
Examine  the  ethereal  solution  iov  fats  and  cholesterin. 

Cholesterin.: — (i.)  Evaporate  a  little  of  the  ethereal  solution  in 
a  watch-glass,  and  add  a  drop  of  strong  H^SO^.  A  red  colour 
indicates  cholesterin.  (2.)  Examine  microscopically.  Cholesterin 
crystallises  from  ethereal  solution  in  colourless  needles,  from  solu- 
tion in  boiling  alcohol  in  its  characteristic  plates. 

C.  Analysis  of  Urine. — The  student  must  also  practise  the 
analysis  of  urines  containing  one  or  more  abnormal  constituents, 
and  he  must  also  practise  the  estimation  of  the  quantity  of  the 
more  important  substances  present.  Both  sets  of  processes  must  be 
done  over  and  over  again,  in  order  that  he  may  perfect  himself  in 
the  methods  in  common  use. 


PART  IL-— EXPERIMENTAL  PHYSIOLOGY. 


Instniinents,   &c.,   to  be  provided    by  each   Student.— J5e/o re 

beginning  the  experimental  part  of  the  course j  each  student 
must  provide  himself  with  the  following : — A  large  and  a  small 
pair  of  scissors ;  a  large  and  a  fine  pointed  pair  of  forceps  ; 
a  small  scalpel ;  a  blunt  needle  or  "  seeker  "  in  a  handle  ; 
pins ;  fins  silk  thread  ;  watch-glasses ;  narrow  glass  rod  drawn 
out  at  one  end  to  act  as  a  ^^  seeker  "  ;  two  cameV s-hair  brushes 
of  medium  size.  It  is  convenient  to  have  them  all  arranged  in 
a  small  case. 


PHYSIOLOGY  OF  MUSCLE  AND  NERVE. 


LESSON  XXV. 


GALVANIC  BATTERIES  AND   OALVANOSCOPE. 


1.  DanieU's  Cell  consists  of  a  glazed  earthenware  pot  with  a 
handle  (fig.  80),  and  containing  a  saturated 
sohition  of  copper  sulphate.  Crystals  of  copper 
sulphate  are  placed  in  it  to  keep  the  solution 
saturated.  The  pot  is  about  18  cm.  high,  and 
9  cm.  in  diameter.  In  the  copper  solution  is 
placed  a  roll  of  sheet-copper,  provided  with  a 
binding  screw.  Within  is  a  porous  unglazed 
cylindrical  cell  containing  10  p.c.  solution  of 
sulphuric  acid.  A  well  amalgamated  rod  of 
zinc,  provided  at  its  free  end  with  a  bind- 
ing screw,  is  immersed  in  the  acid.  The  zinc 
is  the  negative  pole  or  Cathode  ( - ),  and  the  copper  the  positive 
pole  or  Anode  (  +  ). 


158 


PRACTICAL   PHYSIOLOGY. 


[xxv. 


2,  Wilke's  Pole-Reagent  Paper. — This  is  a  convenient  method  for  deter- 
mining the  (  -  )  pole  in  any  combination.  Moisten  one  of  the  papers,  place  it 
on  a  clean  piece  of  glass,  and  touch  the  surface  with  the  two  wires  coming 
from  the  battery  ;  a  red  spot  indicates  the  negative  pole. 

3.  Amalgamation  of  the  Zinc. — (a.)  The  zinc  should  always 
be  weU  amalgamated.  When  a  cell  hisses  the  zinc  requires  to 
be  amalgamated.  Dip  the  zinc  in  lo  p.c.  sulphuric  acid  until 
effervescence  commences.  Lift  it  out  and  place  it  on  a  shallow 
porcelain  plate.  Pour  some  mercury  on  the  zinc,  and  with  a 
piece  of  cloth  rub  the  mercury  well  over  the  zinc.  Dip  the  zinc 
in  the  acid  again,  and  then  scrub  the  surface  with  a  rag  under  a 
stream  of  water  from  the  tap.  CoUect  all  the  surplus  mercury 
and  place  it  in  the  bottle  labelled  "Amalgamation  Mixture." 
Take  care  that  none  of  the  mercury  gets  into  the  soil-pipe.      A 

very  convenient  method  is  to 
dip  the  zinc  into  a  thick-walled 
glass  tube  containing  mercury 
and  sulphuric  acid.  For  con- 
venience the  tube  is  fixed  in  a 
block  of  wood. 

(b.)  The  following  is  another  con- 
venient * '  Amalgamation  Mixture  "  : 
— Witli  the  aid  of  gentle  heat  dissolve 
4  parts  of  mercury  in  5  parts  of 
nitric  acid  and  15  parts  of  hydro- 
chloric acid,  and  then  add  20  parts 
of  hydrochloric  acid.  The  zincs,  after 
being  well  cleaned,  as  directed  above, 
are  dipped  into  this  mixture,  or  the 
mixture  may  be  applied  to  the  clean 
zinc  by  means  of  a  brush. 

N.B. — After  using  a  battery 
the  zincs  must  be  washed  and 
dried,    the    porous    cells    must 
be  carefully  washed,  and  com- 
^■'"'i'Jlir    pletely    immersed    in    a    large 
Yi  ;        -]'-n   It  quantity    of    water,    frequently 

renewed. 

4.  Grove's  Cell  (fig.  81)  consists  of  an  outer  glazed  earthenware, 
glass,  or  ebonite  jar,  containing  amalgamated  zinc  and  10  p.c. 
sulphuric  acid.  In  the  inner  porous  cell  is  placed  platinum  foil 
witii  strong  nitric  acid.  The  ])lafcinum  is  the  +  positive  pole  or 
anode,  the  zinc  the  -  negative  pole  or  cathode.  For  physiological 
purposes,  the  small  Grove's  cells,  about  7  cm.  in  diameter  and  5  cm. 
in  height,  are  very  convenient.     When  in  use  the  battery  ought  to 


XXV.] 


GALVANIC   BATTERIES   AND   GALVANOSCOPE. 


159 


be  placed  in  a  draught  chaml  er  to   prevent   the    nitrous   fumes 
from  affecting  the  experimenter. 

5.  Bichromate  Cell  (fig.  82).— This 
consists  of  a  glass  bottle  containing 
one  zinc  and  tw)  carbon  plates  im- 
mersed in  the  following  mixture  : — 
Dissolve  I  part  of  potassic  bichromate 
in  8  parts  of  water,  and  add  i  part  of 
sulphuric  acid.  The  zinc  is  attached 
to  a  rod,  which  can  be  raised  when  it 
is  desired  to  stop  the  action  of  the 
battery.  This  cell  is  convenient 
enough  when  it  is  not  necessary  to 
use  a  current  of  perfectly  constant  in- 
tensity. 

6.  Leclanche  Cell. — The  positive 
plate  is  zinc  in  ammonium  chloride 
solution  (Zinc  -  pole).  The  negative 
plate  is  carbon  with  manganese 
dioxide  in  the  same  solution  (Car- 
bon +  pole). 

Other  forms  of  batteries  are 
used,  but  the  foregoing  are  suffi- 
cient for  the  purposes  of  these 
exercises. 

7.  The  Galvanoscope  or  De- 
tector. 

(a.)  Charge  a  DanielFs  cell 
and  attach  a  copper  wire  to 
the    negative    pole    (zinc),    and 

another  to  the  positive  pole  (copper).  On  bringing  the  free  ends 
of  the  two  wires  together  the  circuit  is  made,  and  a  current  of 
continuous,  galvanic,  or  voltaic  electricity 
circulates  outside  the  battery  from  the  + 
to  the  -  pole.  Prove  the  existence  of  this 
current  by  its  effect  on  a  magnetic  needle. 

(/;.)  Use  a  vertical  galvanoscope  or  de- 
tector (fig.  83),  in  which  the  magnetic  need  e 
is  so  loaded  as  to  rest  in  a  vertical  position. 
A  needle  attached  to  this  moves  over  a 
semicircle  graduated  into  degrees.  Con- 
nect the  wires  from  the  +  and  -  poles  of  the 
Daniell's  battery  with  .the  binding  screws  of 
this  instrument,  and  note  that  when  the 
circuit  is  made  the  needle  is  deflected  from  ^°'  ^ 

its  vertical  into  a  more  or  less  horizontal  position,  but  the  angle 


Fig,  82.— Bichromate  Cell.  A.  The  glass 
vessel ;  K,  K.  Carbon  ;  Z.  Zinc  ;  D,  E. 
Binding  screws  for  the  wires ;  B.  Rod  to 
raise  or  depress  the  zinc  in  the  fluid  ;  C. 
Screw  to  fix  B. 


-Detector. 


l6o  PRACTICAL  PHYSIOLOGY.  [XXVL 

of  deflection  is  not  directly  proportional  to  the  current  passing  in  the 
instrument.  Break  the  circuit  by  removing  one  wire,  and  notice 
that  the  needle  travels  to  zero  and  resumes  its  vertical  position. 
The  detector  made  by  Stohrer,  of  Leipzig,  is  a  convenient  form. 

8.  Effect  of  Constant  or  Voltaic  Current  on  the  Tongue. — 

Apply  the  free  ends  of  the  wires  to  the  top  of  the  tongue  and  note 
tlie  effect  of  the  current ;  or  a  key  may  be  placed  in  the  circuit. 
The  physiological  effects  of  a  moderate  constant  current  are  but 
slight  on  the  sensory  nerves  of  the  tongue,  there  being  perhaps  a 
slight  metallic  taste. 

Electrical  Units  are  :— The  unit  of  current  is  an  ampere,  the 
unit  of  resistance  an  ohm,  and  the  unit  of  pressure  a  volt.  The 
pressure  or  potential  of  a  Darnell's  cell  is  about  i  volt.  One 
ampere  current  is  obtained  by  i  volt  pressure  through  i  ohm 
resistance,  through  20  ohms  ^V  ampere.  The  internal  resistance 
of  an  ordinary  cell  varies  from  i  to  10  ohms. 


LESSON  XXVL 

ELECTRICAL  KEYS— RHEOCHORD. 

It  is  convenient  to  make  or  break — i.e.,  close  or  open — a  current 
by  means  of  keys,  of  which  there  are  various  forms. 

1.  Du  Bois  Key  (fig.  84). — It  consists  of  a  plate  of  vulcanite, 
attached  to  a  wooden  or  metallic  framework  which  can  be  screwed 
to  a  table.  Two  oblong  brass  bars  (II.  and  III.),  each  provided 
with  two  binding  screws,  are  fixed  to  the  ebonite,  while  a  movable 
brass  bar  (IV.)  with  an  ebonite  handle  is  fixed  to  one  of  the  bars, 
and  can  be  depressed  so  as  to  touch  the  other  brass  bar. 

Two  Ways  of  Using  the  Du  Bois  Key. 

2.  (i.)  When  the  key  is  closed  the  current  is  made,  and  when  it  is 
0}>ene'l  the  current  is  broken  (fig.  85).  Apparatus. — Daniell's  cell 
and  detector,  three  wires,  and  a  Du  Eois  key  screwed  to  a  table. 

(a.)  As  in  the  scheme  (fig.  85)  connect  one  wire  from  —  pole  of 
the  battery  to  one  brass  bar  of  the  key.  Connect  the  other  brass 
bar  Avith  one  binding  screw  of  the  detector.  Connect  by  means  of 
the  third  wire  the  other  binding  screw  of  the  detector  with  the  + 
pole  of  the  cell. 

(h.)  On  depressing  the  key  (z.e.,  making  the  circuit)  the  needle 
is  deflected,  on   raising  it  {i.e.,  breaking   the  circuit)  the  needle 


XXVI.] 


ELECTRICAL    KEYS — RHEOCHORD. 


161 


passes  to  zero.     This  method  of  using  the  key  we  may  call  that  for 
"  making  and  breaking  a  current." 

3.  (2.)  When  the  key  is  closed  the 
current  is  said  to  he  "  short-circuited." 
Apparatus. — Darnell's  cell,  detector, 
four  wires,  and  a  Du  Bois  key. 

(a.)  As  in  sclieme  (fig.  86)  connect 
the  +  pole  of  the  battery  to  the  outer 
binding  screw  of  one  brass  bar  of  the 
key,  and  the  -  pole  to  the  outer  binding 
screw  of  the  other  brass  bar.  Then 
connect  the  inner  binding  screws  of 
both  brass  bars  with  the  detector. 

(/>.)  Observe  when  the  key  is  de- 
pressed or  closed,  there  is  no  deflection 
of  the  needle,  i.e.^  when  the  current  is 
cut  off  from  the  circuit  beyond  the  key 
or  bridge ;  when  the  key  is  raised,  the 
needle  is  deflected.  When  the  key  is 
depressed,  the  current  is  said  to  be 
"  short-circuited,"  for  the  key  acts  like 
a  bridge,  and  so  a  large  part  of  the 
current  passes  through  it  back  to  the 
battery,  while  only  an  excessively  feeble 
current  passes  through  the  wires  beyond 
the  key ;  so  feeble  is  it  that  it  does  not 


Fig.  84.— Du  LoisReymoncrs  Key. 


affect  a  nerve.     On  raising  the  key,  the  whole  of  the  current  passes 


^^^ 


Fig.  85.— Scheme  of  Du  Bois  Key. 
B.  Battery  ;  K.  Key ;  N.  Nerve ; 
M.  Muscle. 


Fig.  86.— Scheme  of  Du  Bois  Key 
forShort-Circuitiiig.  N.  Nerve  ; 
M.  Muscle ;  B.  Battery ;  b".  Key 


through  the  detector  or  nerve,  as  the  case  may  be.     This  method 
of  using  the  key  is  called  the  metliod  of  "  short-circuiting." 

L 


1 62 


PRACTICAL  PHYSIOLOGY. 


[XXVL 


('".)  Test  the  effect  of  a  galvanic  current  by  applying  the 
electrodes  to  the  tip  of  the  tongue. 

N.B. — In  using  the  key  to  apply  an  induction  current  to  excite 
a  nerve  or  muscle,  always  use  this  key  by  the  second  method,  i.e., 
always  place  a  short-circuiting  key  in  the  secondary  circuit. 

4.  Mercurial  Key. — Where  o.  fluid  contact  is  required  the  wires 
dip  into  mercury.  Study  the  use  of  this  key.  It  is  used  in  the 
same  way  as  a  I)u  Bois  key. 

5.  Morse  Key  (fig.  87). — If  it  is  desired  to  make  or  break  a 
current  rapidly,  this  key  is  very  convenient.  If  this  key  be  used 
to  make  and  break  the  primary  circuit,  connect  the  wires  to  B 

and  C ;  when  the  style  of 
the  lever,  Z,  is  in  contact 
with  c,  the  current  does 
not  pass  in  the  primary 
circuit.  On  depressing  the 
handle,  K,  the  primary 
circuit  is  made.  If,  how- 
ever, the  wires  be  con- 
nected to  A  and  B,  the 
current  passes  and  is 
broken  on  depressing  K. 
To  use  this  key  as  a  short- 
circuiting  key,  connect  the  wires  from  the  battery  to  A  and  B,  and 
those  of  the  electrodes  to  A  and  C.  The  current  is  short-circuited 
until  K  is  depressed,  when  the  current  passes  from  C  to  A  through 
the  electrode  wires. 

6.  The  Contact-  or  Spring-Key  (fig.  88)  is  also  very  useful  for 


Fig.  87.— Morse  Key.    The  connections  are  con- 
cealed below,  but  are  B  tol,  Aio  c,  C  to  C. 


—Spring-Key. 


Fig. 


-Plug-Key. 


rapidly  making  and  breaking  a  circuit,  or  for  giving  a  single  shock, 
as  in  estimating  the  work  done  during  the  contraction  of  a  muscle. 
The  current  can  only  pass  between  the  binding  screws  when  the 
metallic  spring  is  pressed  down  The  left  end  of  the  spring  is  in 
metallic  contact  with  the  upper  binding  screw,  while  the  second 


jCXVL] 


ELECTRICAL    KEYS — RHEOCHORD. 


163 


binding  screw  is  similarly  connected  with  the  little  metallic  peg 
at  the  right-hand  end  of  the  fig. 

7.  Plug-Key  (fig.  89). — Two  brass  bars  are  fixed  to  a  piece  of  vulcanite. 
The  circuit  is  made  or  broken  by  inserting  a  brass  plug  between  the  bars. 
Each  brass  bar  is  provided  with  two  binding  screws,  to  which  one  or  two 
wires  may  be  attaclied,  so  that  it  can  be  used  like  a  Du  Bois  key,  either  by 
the  first  or  second  method. 


8.  The  "  Trigger  or  Turn-Over  Key  "  is  referred  to  in  Lesson  XXXV. 

9.  For  Brodie's  "  Rotating  Key,"  see  Lesson  XXVIIL 

Means  of  Graduating  a  Galvanic  Current. — Besides  altering 
the  number,  arrangement,  or  size  of  the  cells  themselves,  we  can 
use  a  simple  rheochord  to  divide  the  current  itself,  the  battery 
remaining  constant,  so  that  weak  constant  currents  of  varying 
strength  can  thus  be  easily  obtained. 

10.  The  Simple  Rheochord  consists  of  a  brass  or  German-silver 
wire,  about  20  ohms  resistance  and  i  metre  in  length,  stretched 
longitudinally  along  a  board,  and  with  its  ends  connected  to 
binding  screws  and  • 
insulated  (fig.  90).  On 
the  wire  there  is  a 
"  slider "  which  can 
be  pushed  along  as 
desired.  Apparatus. 
— Simple  rheochord, 
Daniell's  cell,  detector, 
Du  Bois  key,  five 
wires. 

(a.)  Arrange  the  ex- 
periment as  in  fig.  90. 
When  the  slider  S  is 


Fia 


.  90.— Scheme  of  Simple  Rheochord.    B.  Battery  ; 
K.  Key  ;  W,  R.  Wire  ;  S.  Slider  ;  X>.  Detector. 


hard  up  to  W,  practically  all  the  electricity  passes  along  the  wire 
(W,  R)  back  to  the  battery. 

(6.)  Pull  the  slider  away  from  W,  and  in  doing  so,  the  resist- 
ance in  the  detector  circuit  is  diminished,  and  some  of  the  elec- 
tricity passes  along  the  detector  circuit  or  the  "  deriving  circuit " 
and  deflects  the  needle.  The  deflection  is  greater — but  not  pro- 
portionally so— the  further  the  slider  is  removed  from  W.  The 
deflection  is  nearly  proportional  to  the  distance  of  the  shder  from 
W,  when  the  resistance  in  the  detector  circuit  is  great  compared 
with  that  of  the  rheochord,  which  is,  of  course,  the  case  when  a 
tissue  occupies  the  place  of  the  detector. 


164 


PRACTICAL    PIIYSIOLOGr. 


[xxvi. 


{c.)  Make  a  table  showing  the  extent  of  deflection  of  the  needle 
of  the  detector  according  to  the  distance  of  S  from  W. 

11.  The  wire  of  the  rheochord  may  be  arranged  as  in  fig.  91  ; 
a  slider,  S,  S,  consisting  of  an  ebonite  cup  filled  with  mercury, 
can  be  moved  along  the  wires.  !Make  connections  as  in  fig.  91. 
Observe    as    tlie  mercury  cup  is  pulled  away  from  the  binding 


Fig.  91.— Rheochord  witli  Hg-Slider,  S.  S.    B.  Battery ;  K.  Contact  Spring-Key; 
E.  Ebctiudes ;  N.  Nerve  or  Detector. 

screws  there  is  a  greater  deflection  of  the  needle,  but  the  deflection 
is  not  in  proportion  to  the  distance  of  the  cup.  Make  a  table  of 
your  results. 


Distance  of  Hg- 

Deflection  of  Gal- 

Bridge in  cm. 

vanometer. 

I 

I 

2 

2*5 

3 

4 

4 

6 

10 

9  5 

15 

II 

20 

12*5 

30 

14 

The  resistance  in  the  rheochord  circuit  is  low  as  compared  with 
that  in  the  principal  circuit.  By  means  of  the  slider  the  resistance 
in  the  deriving  circuit  can  be  increased  or  diminished,  and,  con- 
sequently, the  magnitude  of  the  current  diverted  into  the  principal 
circuit.  The  rheochord  also  afl'ords  a  means  of  dividing  a  current 
into  two  parts,  according  to  the  respective  resistances  in  the 
two  circuits.  A  rheochord  is  also  used  to  compensate  any  current 
of  injury  in  nerve  and  muscle  in  rheotonic  experiments. 

12.  Simple  Rheochord. — The  most  convenient  form  is  that 
shown  in  fig.  92,  and  is  that  used  in  the  Physiological  Laboratory 


XXVI.] 


ELECTRICAL   KEYS — RHEOCHORD. 


i6s 


of  Oxford.  It  consists  of  a  German-silver  wire  about  20  ohms 
resistance,  wound  round  ebonite  pegs  fixed  at  equal  distances  at 
the  opposite  ends  of  a  wooden  board.  The  board  is  divided  into 
oblongs,  so  that  each  division  represents  y-J^  part  of  the  whole 
length  of  the  wire,  which  ends  in  two  block  terminals,  A,  B,  each 
provided  with  two  binding  screws.  One  of  tlie  terminals  of  the 
electrodes  is  attached  to  one  terminal  of  the  wire  (A),  and  the  other 
to  the  movable  block  S,  which  represents  a  slider,  and  which  can 
be  applied  to  any  part  of  the  wire,  at  any  distance  from  A.  Owing 
to  the  great  resistance  of  the  nerve  as  compared  with  that  of  the 
wire,  the  current  through  the  nerve  or  muscle  is  in  proportion 
to  the  length  of  wire  between  the  slider  S  and  the  block. 

(a.)  Connect  a  Daniell's  cell  as  in  fig.  92  with  the  two  block 
terminals  (A,  B)  interposing  a  spring-key  (K).  Of  the  electrode 
wires  one  is  connected  to  A,  an  1  the  other  to  the  slider  S, 


Fig.  92.— Simple  Rlieoclionl  as  iisl.1  in  Oxford.  FlQ.  93.— Thomson's  Keverser. 

B.  Battery  ;  A'.  Spring-Key  ;  A.  B.  'I'ei  minala 
of  llheochord  Wire  ;  S.  Slider  ;  N.  Nerve. 

Expose  the  sciatic  nerve  of  a  frog,  and  place  the  electrodes 
under  it,  or  make  a  nerve-muscle  preparation  and  stimulate  the 
nerve.  Place  the  slider  close  to  A,  there  is  no  response  either  at 
make  or  break.  Place  the  slider  at  different  distances  from  A, 
and  note  when  contraction  occurs  at  make. 

13.  Pohl's  Commutator.  —  Sometimes  it  is  desired  to  send  a  current 
through  either  of  two  pairs  of  wires.  This  is  done  by  means  of  Fold's 
commutator  wilhoxt  the  cross-bars  (Lesson  XXXIII.,  fig.  ii2)._  At  other 
times  it  is  desired  to  reverse  the  direction  of  a  current.  This  is  done  by 
Pohl's  commutator  with  cross-bars. 


i66 


PRACTICAL  PHYSIOLOGY. 


[XXVIL 


14.  Thomson's  Reverser  (fig.  93)  may  be  used  to  reverse  the  direction  of  a 
constant  current.  The  wires  from  the  battery  are  connected  to  the  two  lower, 
and  those  from  the  electrodes  to  the  upper  binding  screws.  The  binding 
screws  are  four  in  number,  and  placed  behind  the  circular  disc  seen  in  the 
figure.  When  the  handle  is  horizontal  the  current  is  shut  off  from  the 
electrodes,  while  the  direction  of  the  current  is  reversed  by  raising  or 
lowering  the  handle.  This  instrument  is  used  solely  for  reversing  the 
direction  of  a  current. 


LESSON  XXVII. 


INDUCTION  MACHINE— ELECTRODES. 

1.  Induced  or  Faradic  Electricity  is  most  frequently  employed 
for  physiological  purposes.  Induction  shocks  are  of  short  dura- 
tion, while  they  are  .physiologically  very  active,  and  they  may  be 
employed  as  single  shocks,  or  a  succession  of  shocks  may  be  applied. 
Indeed,  the  fact  th.it  the  application  of  successive  induction  shocks 


FlO.  94— Induction  Apparatus  of  Du  Bois-Reymond.  R.  Primary,  R".  Secondary  spiral ; 
B.  Board  on  which  R"  moves ;  /.  Scale ;  +  - .  Wires  from  battery ;  P",  P".  Pillars  ; 
H.  Neef's  hammer;  R.  Electro-magnet;  S.  Binding  screw  touching  the  steel  spring 
{H)\  S',  and  S".  Binding  screws  to  which  are  attached  wires  when  Neefs  hammer 
is  not  required. 

but  slightly  impairs  the  physiological  activity  of  the  tissues,  and 
that  the  intensity  of  these  shocks  can  be  accurately  graduated,  make 
induced  electricity  so  valuable  as  a  stimulus  in  physiological 
experiments. 

2.  Induction  Apparatus  of  Du  Bois-Reymond. — In  fig.  94  the 
primary  coil  (R')  consists  of  about  150  coils  of  thick  insulated 
copper  wire,  the  wire  being  thick  to  offer  slight  resistance  to  the 


XXVII.]  INDUCTION   MACHINE — ELECTRODES.  I67 

galvanic  current.  The  secondary  coil  (R")  consists  of  6000  turns 
of  thin  insulated  copper  wire  arranged  on  a  wooden  bobbin ;  the 
whole  spiral  can  be  moved  along  the  board  (B)  to  which  a  milli- 
metre scale  (1)  is  attached,  so  that  the  distance  of  the  secondary 
from  the  primary  spiral  may  be  ascertained.  At  one  end  of  the 
apparatus  is  a  Wagner's  hammer  as  adapted  by  Neef,  which 
is  an  automatic  arrangement  for  making  and  breaking  the  primary 
circuit.  When  JSTeef's  hammer  is  used  to  obtain  what  is  called  an 
interrupted  current,  or  "  repeated  shocks,"  the  wires  from  the 
battery  are  connected  as  in  the  figure,  but  when  single  shocks  are 
required,  the  wires  from  the  battery  are  connected  with  a  key,  and 
this  again  with  the  t^vo  terminals  of  the  primary  spiral,  S" 
and  S'". 

Suppose  we  place  the  secondary  coil  hard  up  over  the  primary, 
and  consider  this  as  zero,  then  an  index  on  the  side  of  the  slot  will 
give  the  distance  in  millimetres  of  the  secondary  from  the  primary 
coil,  the  current  being  strongest  when  the  secondary  coil  is  com- 
pletely over  the  primary,  and  diminishing  as  the  secondary  is 
removed  from  the  primary. 

3.  New  Form  of  Inductorium.  — Fig.  96  shows  an  inductorium  where  the 
secondary  spiral  moves  vertically  in  a  slot,  and  is  compensated  by  means  of  a 
counterpoise,  so  that  it  moves  easily.  It  is  used  in  the  same  way  as  the 
other  form. 

4.  Graduated  Induction  Apparatus. — In  the  ordinary  apparatus  the  dis- 
tance between  the  secondary  and  primary  spirals  is  indicated  by  a  millimetre 
scale  attaclied  to  the  instrument.  When  the  secondary  spiral  is  moved  along 
equal  distances,  there  is  not  a  corresponding  increase  or  decrease  in  the  in- 
duced current ;  on  the  contrary,  the  strength  of  the  induced  currents  under- 
goes a  very  unequal  change.  Fick  and  Kronecker  use  a  graduated  induction 
apparatus  ;  one  side  of  the  slot  is  provided  with  a  millimetre  scale,  and  the 
other  is  divided  into  units. 

5.  Bowditch's  Rotating  Secondary  Spiral.— The  secondary  spiral  is  with- 
drawn from  the  primary  to  the  unit  mark  30  on  the  scale.  The  secondary 
spiral  rotates  on  a  vertical  axis,  so  that  it  can  be  placed  at  varying  angles  with 
the  primary.  In  proportion  as  it  is  rotated  from  its  conaxial  position  the 
current  is  diminished.  The  student  may  test  this  by  removing  the  secondary 
spiral  from  the  slot  and  placing  it  at  variable  angles  to  the  primary  spiral. 

6.  Ewald's  Sledge  Coil. — This  coil  is,  with  the  exception  of  the  interrupting 
arrangement,  in  every  respect  similar  to  the  ordinary  Du  Bois-Reymond  coil ; 
the  iron  core  (fig.  95,  K)  is  arranged  movable,  and  the  secondary  coil  slides 
over  the  primary  and  can  be  adjusted  in  any  position  by  means  ef  a  rack  and 
pinion  arrangement.  The  interrupter  consists  of  an  upright  electro-magnet, 
over  the  poles  of  which  swings  a  small  steel  bar-magnet ;  this  magnet  forms 
the  bottom  end  of  a  pendulum  which  swings  with  very  little  friction,  auu  is 
counterbalanced  on  its  upper  end  by  a  small  weight. 

The  electro-magnet,  when  traversed  by  the  current,  becomes  magnetised  in 
such  a  way  that  its  ])oles  are  the  same  as  those  of  the  little  bar-magnet  abovo 
it,  thus  repelling  the  latter,  the  swing  of  which  is  limited  by  the  stop 
spring  B. 


i6S 


PRACTICAL    PHYSIOLOGY. 


[XXVIL 


The  magnetic  circuit  now  being  broken,  the  pendulum  swings  back  until 
it  again  touclies  the  contact  D,  when  it  is  repelled  again,  and  so  on. 

According  to  the  position  which  is  given  to  the  spring  by  means  of  the 
milleil  heail  A,  the  amplitude  and  speed  of  the  interrupter  swings  can  be 
varied  between  the  limits  of  i  and  200  per  second. 

Z,  Z  are  the  battery  terminals  ;  P  and  S  the  terminals  for  primary  and 
secondary  current  (tig.  95). 

7.  Hand-Electrodes  (fig.  97).  —  (a. )  Take  a  piece  of  double  or  twin  wire  (No. 
16)  enclosed  in  gutta-percha  (that  used  for  electric  bells),  about  6-7  cm.  long 
(2.^-3  inches).  Remove  the  gutta-percha  from  the  ends.  By  means  of  a  file 
taper  one  pair  of  ends  to  blunt  points,  to  the  other  ends  solder  ])ieces  60-90 
cm.  long  ( 2-3  feet)  of  thin  copper  wire.  Coil  the  thin  Avires  round  a  glass  or 
wooden  rod  to  make  them  into  a  spiral,  and  to  their  free  unattached  ends 
solder  thicker  coj.per  wire  i  inch  long. 

(b.)  Take  two  pieces  of  flexible  gutta-percha  coated  wire  (No.  20)  60  cm. 
long,  and  two  pieces  of  thick  glass  tubing  8  cm.  long,  having  a  bore 
sufficient  to  admit  the  wire.     Push  a  wire  through  each  tube,  and  allow 


Fia.  95.— Ewald's  Sletige  Iiidncturiuni.  S".  Spcoiulary  coil  moved  by  milled  head  jR;  K. 
Core  of  primary  coil;  A.  Milled  h"ad  to  alter  position  of  stop  B ;  C.  Magnet;  Z,  Z. 
Battery  terminals;  P  and  S.  Those  for  primary  and  secondary  current.  (It  is  made 
by  A.  Hurst  and  Co.,  C6  Feuchurch  Street,  London,  and  costs  £4,  lOs.) 


the  end  of  the  wire  to  project  2  cm.  beyond  the  tube ;  scrape  the  gutta- 
percha off  the  free  ends  of  both  wires.  Fix  the  wires  in  the  glass  tubes 
with  sealing-wax,  and  with  a  well-waxed  thread  bind  the  two  tubes  together. 
Or  use  tAV'o  pieces  of  No.  20  gutta-percha  coated  wire,  each  10  cm.  in 
length,  fix  them  in  glass  tubes,  as  shown  in  the  figure,  by  means  of  gutta- 
percha cement.  To  the  ends  of  the  copper  wires  solder  thin  silk-covered  wires, 
and  to  the  free  ends  of  the  latter  solder  a  short  length  (2  cm. )  of  thick  un- 
coated  copjjcr  wire.  A  very  handy  holder  is  made  by  thrusting  two  fine 
insulated  wires  (No.  36)  through  the  bone  handle  of  a  crotchet-needle. 

8.  Shielded  Electrodes.— For  some  ])urposes,  e.g.,  stimulation  of  the  vagus, 
these  electrodes  are  used,  >.<•.,  the  ])latinum  terminals  are  exposed  only  on  one 
side,  the  other  being  sunk  in  a  uiece  of  vulcanite  (figs.  197,  226).     A  pair 


XXVII.]  INDUCTION    MACHINE — ELECTRODES. 


169 


of  shielded  electrodes  is  easily  made  by  fixing  the  ends  of  two  fine  wires — 
arranged  parallel  to  each  other  and  about  one-eighth  of  an  inch  apart — in  a 
thin  layer  of  gutta-percha  cement.  A  little  of  the  cement  is  scraped  oflf  to 
expose  a  small  piece  of  both  wires. 

9.  Du  Bois-Reymond  Electrodes  (fig.  98).— The  two  wires  end  in  triangu- 
lar pieces  of  platinum  (P)  which  rest  on  a  glass  plate.  The  whole  is  sup- 
ported on  a  stand  (V),  and  can  be  moved  in  any  direction  by  the  universal 
Joint  (B). 


FlQ.  96.— Inductorium  with  Secondary 
Coil  Moving  in  a  Vertical  Slot. 


TlQ.  97.  —  Hand  Elec- 
trodes, such  as  a  Stu- 
dent is  required  to 
make  for  himself. 


10.  Polarisation  of  Electrodes.— When  a  constant  current  is 
led  through  a  nerve  for  some  time  it  causes  electrolysis  where  the 
metallic  wires  come  into  contact  with  the  liquids  of  the  nerve. 
The  excitability  of  the  nerve  is  altered  by  the  secondary  electro- 
motive changes  thus  produced,  so  that  the  nerve  is  thereby  excited, 
and  the  muscle  is  thrown  into  contraction.  Apparatus. — Elec- 
trodes (fig.  97),  two  wires,  Du  Bois  key,  Daniell's  cell,  frog. 

(a.)  Pith  a  frog  (Lesson  XXIX.  1),  lay  it  belly  downwards  on 
a  frog-plate,  and  expose  one  sciatic  nerve. 


170 


PRACTICAL   PHYSIOLOGY. 


[XXVIL 


(b.)  Screw  the  Du  Bois  key  to  the  table,  place  the  copper  elec- 
trodes under  the  sciatic  nerve,  and  connect  their  other  ends  each 
with  the  outer  binding  screw  of  the  brass  bars  of  the  Du  Bois  key. 
Close  the  key,  and  observe  that  no  contraction  of  the  leg  muscles 
occurs. 

(c.)  Connect  a  Daniell's  cell  with  the  Du  Bois  key.  Open  the 
key  to  allow  the  constant  current  to  pass  through  the  nerve  for 


Fig.  q8.— Du  Bols-Tleymoud's  Platinum  Electrodes.    The  nerve  is  placed  over  the  two 
pieces  of  platinum,  P,  which  rest  on  glass ;  B.  Universal  joint ;  F.  Support. 

three  or  four  minutes,  and  observe  that  there  is  no  contraction  as 
long  as  the  constant  current  is  passing.  Close  the  key,  i.e.j  short- 
circuit  the  battery,  and  at  once  a  contraction  occurs.  Remove  the 
battery,  close  and  open  the  key.  Contractions  occur,  but  they 
gradually  get  feebler  as  the  polarisation  ceases.  The  contractions 
are  due  to  polarisation  of  the  electrodes. 

{d.)  If  non-polarisable  electrodes  are  used,  this  does  not  happen. 

11.  Non-Polarisable  Electrodes.     See  Lesson  XLL 


xxvm.] 


SHOCKS  AND   CURRENTS. 


171 


LESSON  XXVIII. 

SINGLE  INDUCTION  SHOCKS  —  INTERRUPTED 
CURRENT—BREAK  EXTRA-CURRENT  —  HELM- 
HOLTZ'S  MODIFICATION. 

1.  Single  Induction  Shocks. — Apparatus.— Daniell's  cell,  in- 
duction machine,  wires,  two  Du  Bois  keys  (or  one  Du  Bois  and 
one  spring  or  mercury  key),  and  electrodes. 

(a.)  Make  connections  as  in  fig,  99.  The  key  in  the  primary 
circuit — preferably  a  mercury  key — is  used  to  make  or  break  the 
primary  current.  To  the  binding  screws  of  the  secondary  coil 
attach  two  wires,  and  connect  them  to  the  short-circuiting  Du 
Bois  key,  and  to  the  latter  the  electrodes. 


Fia.  99.— Scheme  for  Single  Induction  Shocks.     B.  Battery  ;  K,  K'.  Keys ;  P.  Primary, 
and  S.  Secondary  coil  of  the  induction  machine  ;  N.  Nerve ;  M.  Muscle. 

(b.)  Effect  on  Tongue  of  Single  Induction  Shocks.— Open  the 

short-circuiting  key,  push  the  secondary  coil  pretty  near  to  the 
primary,  and  place  the  points  of  the  electrodes  on  the  tip  of  the 
tongue,  or  hold  them  between  the  forefinger  and  thumb  moistened 
with  water.  Close  the  key  in  the  primary  circuit,  i.e.,  make  the 
circuit,  and  instantaneously  at  the  moment  of  making,  a  shock  or 
prick — the  closing  or  make  induction  shock — is  induced  in  the 
secondary  coil,  S,  and  is  felt  on  the  tip  of  the  tongue  or  finger. 
All  the  time  the  key. is  closed  the  galvanic  current  is  circulating  in 
the  primary  coil,  but  it  is  only  when  the  primary  current  is  made 
or  broken  that  a  shock  is  induced  in  the  secondary  coil. 

(c.)  Break  the  primary  current  by  raising  the  key,  and  instan- 
taneously a  shock — the  opening  or  break  induction  shock — is  felt. 

(d.)  The  break  is  stronger  titan  the  male  shod-.  Push  the 
secondary  coil  a  long  distance  from  the  primary,  and,  while  the 
electrodes  are  on  the  tongue,  make  and  break  the  primary  circuit. 
Gradually  move  the  secondary  near  the  primary  coil.  The  break 
shock  is  felt  first,  and  on  pushing  the  secondary  nearer  the  primary 


172  PRACTICAL   PHYSIOLOGY.  [XXVIIL 

coil  both  shocks  are  felt,  but  the  break  is  stronger  than  the  make 
shock. 

Note  that : — 

(i.)  The  break  shock  is  the  stronger. 

(ii.)  On  approximating  the  secondary  to  the  primary  coil,  a 
shock   is   felt  at  make  also,  t.e.,  when  the  primary 
circuit  is  made, 
(iii.)  If   the  primary  circuit  be  kept  closed,    i.e.,    made,  no 

shock  is  felt. 
(iv.)    The    shocks    increase     in    intensity    the    nearer    the 
secondary  coil  is  to  the  primary 
N.B. — Make  a  table  of  the  results  showing  the  distance  of  the 
secondary  coil  from  the  primary  when  testing  the  relative  effects 
of  M.  and  B.  shocks. 

Single  M,  and  B.  Induction  Shocks  (i  Daniell). 

Distance  of  Secondary  Coil  Effect  on  Tongue, 

from  Primary  in  cm.  M.  B. 

19  o  o 

ig  O  Slight  shock. 

17  O  Stronger  shock. 


9  Slight  shock.  Maximum  shock, 

8  Stronger  shock.  ,,  ,, 

7  Maximum  shock,  ,,  ,, 

(«.)  Remove  the  secondary  spiral  from  its  slot,  and  place  it  in  line  with 
and  about  15  cm.  fiom  the  primary.  Rotate  the  secondary  coil  so  as  to  place 
it  at  variable  angles  with  the  primary.  Make  and  break  the  primary  circuit, 
and  test  how  the  strength  of  the  induced  current  varies  with  the  extent  of 
rotation  of  the  secondary  spiral. 

2.  Interrupted  Cunent,  i.e.,  Repeated  Shocks,  by  using  Neef  s 
Hammer — {Alternating  CuiTents) — Faradisation. 

{'(.)  Connect  the  battery  -svires  (fig.  100)  to  P'  (  +  )  and  P"(  -  ). 
Introduce  a  Du  Bois  key  as  for  the  make  and  break  arrangement. 
The  automatic  vibrating  si)ring,  or  Keef's  hammer,  is  now  included 
in  the  primary  circuit.  Set  the  spring  vibrating.  'Close  the 
key  in  the  primary  circuit.  The  spring,  H,  is  attracted  by  the 
temporary  magnet,  B',  thus  breaking  the  contact  between  the 
spring,  H,  and  the  screw,  S',  and  causing  a  break  shock  in 
the  secondary  coil.  B'  is  instantly  demagnetised,  the  spring 
recoils  and  makes  connection  with  S',  and  causes  a  make  shock. 
Thus  a  series  of  make  and  break  induction  shocks  following  each 
other  with  great  rapidity  is  obtained,  but  the  make  and  break 
shocks  are  in  alternately  opposite  directions. 


XXVIII.] 


SHOCKS    AND   CURRENTS. 


173 


(b.)  Effect  on  Tongue.— AVhile  Ncof's  hammer  is  vibrating, 
apply  the  electrodes  to  the  tongue  as  before,  noting  the  effect  pro- 
duced and  how  it  varies  on  altering  the  distance  between  the 
secondary  and  primary  coils. 


Fia.  too.  -Induction  Coil  arranged  for  interrupted  or  repeated  shocks,  with 
Neef's  Hammer  in  the  Primary  Circuit. 


(c.)  Note  also  how  the  strength  of  the  induced  shocks  varies  with  the 
angular  deviation  of  the  secondary  spiral,  the  distance  between  the  two 
spirals  being  kept  constant  (p.  172). 

3.  The  Break  Extra-Current  of  Faraday. — When  a  galvanic 
current  traversing  tlie  primary  coil  of  an  induction  macbine  is 
made  or  broken,  each  turn  of  the  wire  exerts  an  inductive  influence 
on  the  others.  When  the  current  is  ma'fe,  the  direction  of  the 
extra-current  is  arjainst  that  of  the  battery  current,  but  at  break  it 
is  in  the  same  direction  as  the 
battery  current.  Apparatus. — 
Daniell's  cell,  two  Du  Bois  keys, 
five  wires,  primary  coil  of  in- 
duction coil,  electrodes  (or  nerve- 
muscle  preparation). 

(a.)  Arrange  the  apparatus 
accoi'ding  to  the  scheme  (fig. 
1 01).  Notice  that  both  keys 
and    the    primary    coil    of    the 

induction    machine     are    in     the  Fio.ioi.— Scheme  of  the  Break  Extra-Cuneut 
..      ,,        ,  ,     .  B.  Battery;  K.  and  K".  Keys;  P.  Pnmar> 

primary   circuit,    the   keys  being      coil ;  N.  Nerve ;  M.  Muscle. 

so    arranged    that     either    the 
primary  coil,  P, 
short-circuited. 


or   the   electrodes   attached   to   key  K',  can  be 


174 


PRACTICAL  PHYSIOLOGY. 


[XXVITI. 


(A.)  Test  (a)  either  by  electrodes  applied  to  the  tongiie,  or  (^) 
by  means  of  a  nerve-muscle  preparation  {ft  to  be  done  after  the 
student  has  learned  how  to  make  a  nerve-muscle  preparation). 

(r.)  Close  the  key  K,  thus  short-circuiting  the  coih  Open  and 
close  key  K'.     There  is  very  little  effect. 

(iL)  Open  K,  the  current  passes  continuously  through  the 
primary  coil.  Open  key  K';  a  marked  sensation  is  felt,  due  to 
the  break  extra-current. 


4.  Helmholtz's  Modification.  —  The  break  shock  is  stronger 
than  the  make,  and  to  equalise  them  Helmholtz  devised  the 
following  modification  : — 

(a.)  Connect  the  battery  wires  as  before  to  the  two  pillars  (fig. 
loo),  P'  and  P",  or  to  a  and  e  (fig.   102).     In  fig.  102  connect  a 

wire — "  Helmlioltz's  side  wire  " 
— from  a  to  /',  thus  bridging  or 
"  short  -  circuiting  "  the  inter- 
rupter. Elevate  the  screw  (/) 
out  of  reach  of  the  spring  (c), 
hut  raise  the  screw  (d)  until  it 
touches  the  spring  at  every 
vibration.  By  this  means  the 
make  and  break  shocks  are  nearly 
equahsed.  Test  tliis  on  the 
tongue.  Both  shocks,  however, 
are  weaker,  so  that  it  is  necessary 
to  use  a  stronger  battery.  The 
piimary  circuit  is  never  entirely 
broken,  it  is  merely  weakened. 

It  is  always  advantageous, 
when  using  faradic  shocks  for 
physiological  purposes,  to  use 
make  and  break  shocks  of 
nearly  equal  intensity,  i.e.,  use 
Helmholtz's  side  wire.  Why? 
Because  any  "  polarisation "  produced  by  the  one  current  is 
neutrahsed  by  the  other.  This  is  not  the  case  with  the  ordinary 
arrangement,  where  the  break  shock  is  stronger  than  the  make, 
whereby    there   is   a   progressive   summation  of   the   polarisation 


FlO.  102.  —  Helmholtz's  Mndiflcation  of 
Neef  s  Hammer.  As  long  as  c  is  not  in 
contact  with  d,  g  h  remains  magnetic  ; 
thus  c  is  attracted  to  d,  and  a  secondary 
circuit,  a,  b,  e,  d,  e,  is  formed  ;  e  then 
springs  back  again,  and  thus  the  process 
goes  on.  A  new  wire  is  introduced  to 
connect  a  with/.    K.  Battery. 


effects  of  the 


IS   a 
break  shocks. 


5.  To  Approximately  Equalise  Single  Make  and  Break 
Induction  Shocks. 

As  we  have  seen,  the  extra-current  is  the  cause  of  the  greater 
intensity  of  the  break  shock.     If,  however,  the  intensity  of  the 


XXVIII.] 


SHOCKS   AND  CURRENTS. 


175 


extra-current  be  the  same  at  make  and  break,  this  inequality  will 
disappear. 

(a.)  Connect  the  terminals  of   a   Daniell's  cell  with   the   top 
binding  screws  of  an  induction  coil,  as  in  fig.   103,  and  to  the 


FlO.  103. — Arrangement  to  approximately  equalise  M.  and  B.  shocks.     P.  Primary, 
S.  Secondary  coil ;  K.  Key  in  deriving  circuit,  D.  D, 

same  induction  coil  terminals  connect  two  other  wires  with  a 
make  and  break  key  (K)  in  their  circuit  ("  deriving  circuit,"  D,  D). 
Thus  the  primary  current  is  never  broken. 

(b.)  Arrange  the  secondary  coil  with  short-circuiting  key  and 
electrodes. 

{c.)  On  closing  the  key  in  the  deriving  circuit  the  current  in 
the  primary  coil  is  diminished,  and  on  opening  it  the  primary 
current  is  increased.  Induced  currents  of  opposite  directions 
are  thereby  produced,  which,  though  weaker  than  the  make 
induction  shock,  are  approximately  equal  to  each  other. 

6.  'To  Eliminate  either  M.  or  B.  Shocks. — For  this  purpose  the  "  Rotating 
Key  "  devised  by  Gregor  Brodie  is  most  useful.  It  consists  of  a  horizontal 
axis  supported  on  two  ebonite  uprights  fixed  to  an  ebonite  base  (fig.  104). 


FlQ.  104.— Brodie's  "  Rotating  Key  "  to  eliminate  the  AT.  or  B.  shock. 

This  axis  consists  of  two  metal  rods,  A  B  and  C  D,  united  together  by  an 
insulating  piece  of  ebonite,  K,  A  B  })asses  through  a  cup,  E,  cut  in  the  upright 
and  filled  with  moreury.     The  other  rod,   C  D,  is  similarly  connected  to  tlie 


1^6  PRA.CTICAL   PHYSIOLOGY.  [XXIX. 

second  ujnight.  Two  stout  wires,  S,  T,  lead  from  the  two  mercury  cups,  E,  F, 
to  two  binding  screws,  1  and  4  respectively.  Attached  to  the  two  rods  are 
two  metal  arms,  M  and  N.  which  can  be  rotated  round  the  rods  and  clamped 
in  any  position.  These  dip  into  two  mercury  troughs,  P  and  Q,  which  are 
respectively  attached  by  stout  wire  to  two  binaing  screws,  2  and  3. 

The  action  for  which  the  key  was  devised  is  as  follows  : — 

The  primary  circuit  is  connected  with  the  two  screws  3  and  4  ;  the 
secondary  and  a  pair  of  electrodes  with  the  screws  1  and  2.  Then,  as  the 
axis,  A  D,  is  rotated,  the  arm,  M,  first  dips  into  the  trough,  P,  and  the 
secondary  circuit  is  thereby  short-circuited,  and  remains  so  during  the  whole 
time  the  arm,  M.  is  in  the  mercury.  While  this  is  still  in  the  mercury  the 
second  arm,  N,  enters  the  mercury.  Q,  and  the  primary  circuit  is  thus  closed, 
but,  as  the  secondary  is  short-circuited,  the  make  induced  current  does  not 
reach  the  electrodes.  On  rotating  a  little  further,  the  ann,  M,  leaves  the 
mercury,  and  shortly  after  the  aim,  N.  leaves  the  mercury,  Q,  and  the  current 
is  broken.  The  break  induced  current  can  now  pass  through  the  electrodes 
since  the  secondary  circuit  is  not  now  short-circuited. 

By  reversing  the  rotation  only  make  shocks  can  pass  through  the  electrodes, 
the  break  shocks  being  short-circuited. 

The  key  may  also  be  used  in  other  ways.  By  placing  the  two  arms,  M  and 
N",  parallel  to  one  another,  the  key  may  be  used  to  close  two  circuits  simul- 
taneously, e.g.,  a  primary  current,  and  a  current  working  a  signal. 

Further,  by  altering  the  angular  distance  between  M  and  N,  and  having  the 
axis  driven  at  a  constant  rate,  the  key  may  be  used  for  sending  in  two  succes- 
sive stimuli  at  different  intervals  of  time. 


LESSON  XXIX. 


PITHING— CILIARY  MOTION— NERVE-MUSCLE 
PREPARATION— NORMAL  SALINE. 

1.  Pith  a  Frog.  — Wrap  the  body,  fore  and  hind  legs,  in  a  towel, 
leaving  the  head  projecting.  Grasp  the  towel  enclosing  the  frog 
with  the  little,  ring,  and  middle  fingers  and  thumb  of  the  left  hand, 
leaving  the  index-finger  free.  "With  the  index-finger  bend  down 
the  frog's  head  over  the  radial  surface  of  the  second  finger  until 
the  skin  over  the  back  of  the  neck  is  put  on  the  stretch.  With 
the  nail  of  the  right  index-finger  feel  for  a  depression  where  the 
occiput  joins  the  atlas,  marking  the  position  of  the  occipito- 
atlantoid  membrane.  With  a  sharp,  narrow  knife  held  in  the 
right  hand,  di\'ide  the  skin,  membrane,  and  the  medulla  oblongata. 
Withdraw  the  knife,  thrust  a  "  seeker "  into  the  brain  cSvity 
through  the  opening  just  made,  and  destroy  the  brain.  To  prevent 
oozing  of  blood,  a  piece  of  a  wooden  match  may  be  thrust  into  the 
brain  cavity.  If  it  is  desired,  destroy  also  the  spinal  cord  with 
the  seeker  or  a  wire.     The  knife  used  must  not  have  too  broad  a 


XXIX.]  PITHING — CILIARY   MOTION,    ETC.  177 

blade,  else  two  large  blood-vessels  will  be  injured.     The  operation 
bhould  be  performed  witly)ut  losing  any  blood. 

2.  Ciliary  Motion. 

{a.)  Destroy  the  brain  and  spinal  cord  of  a  frog.  Place  the 
frog  on  its  back  on  a  frog-plate  covered  with  cork  well- waxed  or 
coated  with  paraffin.  Divide  the  lower  jaw  longitudinally,  and 
carry  the  incision  backwards  through  the  pharynx  and  oesophagus. 
Pin  back  the  flaps.  Moisten  the  mucous  membrane,  if  necessary, 
with  normal  saline. 

(b.)  Make  a  small  cork  flag,  and  rest  it  on  the  mucous  mem- 
brane covering  the  hard  palate  between  the  eyes.  It  will  be 
rapidly  carried  backwards  by  ciliary  motion  towards  the  stomach. 
Repeat  the  experiment,  and  determine  the  time  the  flag  takes  to 
travel  a  given  distance. 

(c.)  Apply  heat  to  the  preparation,  and  observe  that  the  cork 
travels  much  faster. 

{(l.)  Grains  of  charcoal  or  Berlin  blue  are  carried  backwards  in  a  similar 
manner, 

{e.)  With  a  hot  wire  cauterise  superficially  a  small  area  of  the  mucous 
membrane  in  a  preparation  bestrewn  with  grains  of  charcoal.  The  ciliary 
movement  stops  not  only  at  the  cauterised  area,  but  also  in  a  triangular 
area  whose  apex  is  at  the  burned  point,  and  whose  base  is  directed  towards 
the  oesophagus.  It  would  seem,  therefore,  that  the  movements  of  the  cilia 
in  individual  cells  are  not  independent  of  the  movements  in  neighbouring 
cells. 

3.  Anatomy  of  the  Nerve-Muscle  Preparation.— Before  mak- 
ing this  preparation,  the  student  must  familiarise  himself  with 
the  anatomy  of  the  hind  limb  of  the  frog.  On  a  dead  frog  study 
the  arrangement  of  the  muscles,  as  shown  in  fig.  105.  The  skin  of 
the  frog  is  removed,  the  frog  placed  on  its  belly,  and  the  muscles 
viewed  from  behind.  On  the  outside  of  the  thigh,  the  triceps 
fenwris  (tr),  composed  of  the  rect/is  anterior  (ra),  the  vastus 
externns  (ve),  and  the  vafitus  internus,  not  seen  from  behind.  On 
the  median  side,  the  semi-memhranosus  (.sw),  and  between  the  two 
the  small  narrow  biceps  (b).  The  biceps  is  readily  observed,  at 
the  lateral  margin  of  the  large  semi-membranosus,  by  its  shining 
tendon  in  the  middle  of  the  lower  half  of  the  thigh.  Notice,  also, 
the  coccygeo-iliacus  (ci),  the  (jluteus  (gl),  the  i»jri/ormis  (7;),  and 
tlie  rectus  internns  minor  (ri).  In  the  leg,  the  (jaslrorwmias  (r/), 
with  its  tendo  Achillis,  the  tibialis  anticus  (ta),  and  the  peroneus 
(pe). 

4.  Make  a  Dissection. 

(a.)  Remove  the  skin  from  the  leg  of  a  dead  frog  ;  with  a  blunt 
needle,  called  a  "  seeker  "  or  a  ''  finder,"  or  a  glass  rod  drawn  out  to 

M 


178 


PRACTICAL  PHYSIOLOGY. 


[XXIX. 


a  point,  gently  tear  through  the  fascia  covering  the  thigh  mnscles, 
and  with  the  hhint  point  of  the  finder  se]iarate  the  semi-mem- 
branosus  from  the  biceps,  and  in  the  interval  between  them  observe 
the  sciatic  nerve  and  iho,  femoral  veasels.  Carefully  isolate  both, 
beginning  at  the  knee,  where  the  nerve  divides  into  two  branches 
— the  tibial  and  peroneal — and  work  upwards  (fig.  io6). 


Fro.  105.— The  Muscles  of  the  Left  Leg 
of  a  Frog  from  behind,  d.  Coccy- 
geo-iliacus;  gl.  Gluteus;  p.  Pyri- 
forniis;  ra.  Eectua  anterior;  ve. 
Vastus  exteriius ;  tr.  Triceps ;  ri. 
Eect.  int.  minor :  sm.  Semi-mem- 
branosus;  b.  Biceps;  g.  Gastro- 
cnemius; ta.  Tibialis  anticus ;  pe. 
Peroneus. 


PlO.  106.— ■Distril'ution  of  the  Sciatic 
Nerve  (I.)  of  tlie  Frog  (see  also  fig. 
105).  St.  Semitendinosus;  ad'" 
Adductor  magnus ;  (II.)  its  tibial, 
and  (III.)  peroneal  divisions. 


The  tibial  branch  passes  over  the  knee-joint  towards  the  middle  line,  and 
enters  the  under  surface  of  the  gastrocnemius  ;  the  peroneal  branch  jiassea 
between  the  lateral  tendinous  origin  of  the  gastrocnemius  and  the  tendon  of  the 
biceps,  and  then  under  the  latter. 

{}).)  Follow  the  nerve  right  upwards  to  its  connection  with  the 
vertebral  column,  and  observe  that  it  is  necessnry  to  divide  the 


XXX.]  NERVE-MUSCLE  PREPARATION,  ETC.  1 79 

pyriformis  (p),  and  also  tlie  ilio-coccygoal  muscle,  when  tlie  tlirca 
spinal  nerves — the  ytli,  8th,  and  9th — which  form  the  sciatic  nerve, 
come  hito  view.  It  can  be  seen  from  the  abdominal  side  after 
opening  the  belly  and  removing  the  viscera,  including  the  kidneys. 
On  its  way  from  the  sacral  plexus  to  the  thigh,  it  gives  off  cutan- 
eous and  muscular  branches  for  the  pelvis  and  thigh. 

5.  Double  Semi-Membranosus  and  Gracilis  [Pick's  Method). — I  am  indebted 
to  Prof.  Fick  and  Dr  Schenk  of  "VVilrzburg,  for  showing  me  the  method  of  pre- 
paring this— one  of  the  most  convenient  of  preparations. 

{a.)  After  pithing  a  frog,  and  removing  its  skin  to  expose  the  muscles  of  the 
hind  Hmbs,  remove  the  few  fibres  of  the  rectus  internus  minor  which  are  torn 
across  when  the  skin  is  torn  off.  Divide  the  fascia  at  the  outer  margins  of  the 
semi-membranosus  and  gracihs,  until  the  insertion  of  these  two  muscles  into 
the  knee  is  reached,  then,  with  strong  scissors,  divide  tlxe  leg  bone  just  umler 
the  knee-joint,  so  that  the  osseous  insertion  of  both  muscles  is  retained. 
Divide  the  femur  just  above  the  knee-joint,  and  separate  all  the  muscles  in- 
serted into  it,  save  the  two  muscles  one  is  isolating.  Separate  the  two  muscles 
from  the  other  muscles  of  the  thigh  up  to  the  symphysis.  Leave  the  two 
muscles  in  connection  with  the  symphysis,  divide  the  other  muscles,  disar- 
ticulate the  femur  at  the  acetabulum.  In  preparing  the  n)uscles  in  this  way 
the  semi-tendinosus,  which  lies  between  the  two  on  the  side  towards  the  bone, 
is  usually  left.  It  is  easy  to  separate  it  by  dividing  its  insertion  into  the 
femur,  and  then  its  two  heads  at  the  pelvis. 

[b. )  Make  a  similar  dissection  on  the  opposite  side.  Bore  a  hole  with  an  awl 
through  both  acetabula.     Through  this  a  hook  can  be  placed. 

Thus  we  have  two  muscles  with  nearly  straight  fibres  which  can  be  placed 
"side  by  side,"  thus  giving  a  short  muscle  with  great  sectional  area,  or  they 
can  be  placed  "one  behind  the  other,"  a  piece  of  bone,  the  symphysis  inter- 
vening, thus  giving  a  long  muscle  with  half  the  sectional  area.  This  prepara- 
tion is  extensively  used  by  Prof.  Fick,  and  has  many  advantages. 

6.  Indifferent  Fluids — Normal  Saline. — Dissolve  6  grams  of  dried  sodic 
chloride  in  1000  cc.  of  water.  This  is  the  best  fluid  to  use  to  moisten  tissues 
when  a  large  quantity  is  required.  For  nerve  the  aqueous  humor  of  the  frog's 
eye  is  the  best.  It  can  readily  be  obtained  by  perforating  the  cornea  with  a 
fine  glass  pipette. 


LESSON  XXX, 


NERVE  -  MUSCLE  PREPARATION  —  STIMULATION 
OP  NERVE— MECHANICAL,  CHEMICAL,  AND 
THERMAL  STIMULI. 

1.  Nerve-Muscle  Preparation.  —  Apparatus.  —  Frog,  seeker, 
narrow-bladed  scalpel,  a  small  and  a  large  pair  of  scissors,  forceps, 
towel,  and  a  porcelain  plate. 

(A.)  (a.)  Pith  a  frog,  destroying  the  brain  and  spinal  cord,  and 
place  the  frog  on  its  belly  on  a  frog-plate.     With  scissors  make  an 


i8o 


PRACTICAL  PHYSIOLOGY. 


[xxx. 


incision  through  the  skin  along  the  back  of  one  thigh — say  the  left 
— from  the  knee  to  the  lower  end  of  the  coccyx,  and  prolong  the 
incision  along  the  hack  a  httle  to  tlie  left  of  the  urostyle.  Reflect 
the  skin,  and  expose  the  muscles  shown  in  fig.  105. 

(b.)  Gently  separate  the  semi-membranosus  and  biceps  with  the 
*'  seeker,"  and  bring  into  view  the  sciatic  nerve  and  femoral  vessels. 
Some  use  a  glass  rod  drawn  to  a  thin  prolonged  point,  instead  of  a 
"  seeker."  Still  working  with  the  seeker  and  beginning  near  tlie 
knee,  clear  the  sciatic  nerve,  but  do  not  scratch  or  stretch  the  nerve, 
or  touch  it  with  forceps.  Divide  the  pyriformis  and  iho-coccygeus, 
and  trace  the  nerve  up  to  the  vertebral  column. 

(r.)  Divide  the  spinal  column  above  the  seventh  lumbar  vertebra ; 
seize  the  tip  of  tlie  urostyle  with  forceps,  raise  it,  and  with  the  strong 
scissors  cut  it  clear  from  all  its  connections  as  far  as  the  last  lumbar 
vertebra,  and  then  divide  the  urostyle  itself.  Divide  the  left  ihac 
bone  above  and  below,  and  remove  it  with  the  muscles  attached  to 
it.  The  lumbar  plexus  now  comes  into  view.  Bisect  lengthways 
the  three  lower  vertebrae,  and  use  the  quadrilateral  piece  of  bone 
by  which  to  manipulate  the  nerve.  AVith  forceps  lift  the  fragment 
of  bone,  and  with  it  the  sciatic  nerve ;  trace  the  latter  downwards 
to  the  knee,  dividing  any  branches  with 
fine  scissors.  Keep  the  parts  moist  with 
normal  saline. 

(d.)  Divide  the  skin  over  the  gastroc- 
nemius, and  expose  this  muscle.  Divide 
the  tendo  Achillis  below  its  fibro-cartilage, 
lift  the  tendon  with  forceps  and  detach  the 
gastrocnemius  from  its  connections  as  far  up 
as  the  lower  end  of  the  femur.  Cut  across 
the  knee-joint,  and  remove  the  tibia  and 
fibula  with  their  attached  muscles.  Taking 
care  to  preserve  the  sciatic  nerve  from 
j\  11  injury,    clear   the   muscles   away   from   the 

lt\  ^^  lower  end  of  the  femur,  and  then  divide  the 

femur  itself  about  its  middle.  This  prepara- 
tion (fig.  107)  consists  of  the  gastrocnemius, 
and  the  whole  length  of  the  sciatic  nerve, 
to  which  is  attached  a  fragment  of  bone, 
by  which  the  preparation  can  be  manipulated 
without  injuring  the  nerve.  N.B.— The  nerve  must  not  be  touched 
with  instruments,  neither  stretched  nor  scratched,  nor  allowed  to 
come  into  contact  with  the  skin,  and  it  must  be  kept  moist  with 
normal  saline. 

(B)  (a.)  Another  metliod  is  sometimes  adopted.  Destroy  a  frog's  brain 
and  82)inal  cord.     With  the  left  hand  seize  the  hind  limbs  and  hold  the  frog 


Fig.  107.  —  Nerve  -  >ruscle 
Preparation.  S.  Sciatic 
nerve — the  fragment  of 
the  spinal  column  is 
not  shown  ;  F.  Femur  ; 
and  /.  Tendo  Achillis. 


XXX.]  NERVE-MUSCLE   PREPARATION,   ETC.  l8l 

with  its  belly  downwards.  With  one  blade  of  a  sharp-pointed  pair  of  scissors 
transfix  the  body  immediately  behind  the  shoulder-blades,  and  divide,  the 
spinal  column.  The  head  now  hangs  down,  and  by  its  weight  it  pulls  the 
ventral  from  the  dorsal  parts. 

{b.)  With  the  scissors  divide  the  wall  of  the  abdomen  on  both  sides  j)arallel 
to  the  vertebral  column,  and  remove  the  abdominal  viscera.  With  the  left 
hand  seize  the  upper  end  of  the  divided  spinal  column,  and  with  the  riglit  the 
skin  covering  it,  and  pull.  The  lower  end  of  tlie  trunk  and  the  lower  limbs 
are  denuded  of  skin. 

(c.)  Take  the  thigh  muscles  between  the  thumb  and  forefinger  of  the  left 
hand,  and  with  the  point  of  one  blade  of  a  pair  of  scissors  tear  through  the 
fascia  between  the  biceps  and  semi-membranosus  to  expose  the  sciatic  nerve, 
and  then  proceed  as  directed  in  1. 

2.  Stimuli  may  be  classified  ^as  follows  : — 

(i.)  Mechanical,  e.g.,  cutting  or  pinching  a  nerve  or  muscle. 
(2.)  Chemical,  e.g.,  by  dipping  the  end  of  a  nerve  in  a  saturated 
solution  of  common  salt  or  glycerin. 

(3.)  Thermal,  e.g.,  applying  the  end  of  a  heated  wire  to  the 
nerve. 

( (a.)  Continicous  current. 
(4.)  Electrical —  <  (b.)  Single  induction  shocks, 

(  (c.)  Interrupted  current  or  repeated  shocks, 

3.  Stimulation  of  Muscle  and  Nerve. — It  is  convenient  to 
modify  somewhat  the  physiological  limb,  in  order  to  render  the 
muscular  contraction  more  visible.  Apparatus. — Seeker,  scalpel, 
scissors,  forceps,  straw  flag,  pins,  muscle-forceps,  camel's-hair  brush, 
saturated  solution  of  common  salt  in  a  glass  thimble,  ammonia, 
copper  wire,  spirit  lamp  or  gas-flame. 

4.  Mechanical  Stimulation. 

(a.)  Destroy  the  brain  and  spinal  cord  of  a  frog  (Lesson  XXX.  1). 
Prepare  a  nerve-muscle  preparation,  isolat- 
ing the  sciatic  nerve,  but  modify  the  sub- 
sequent details  as  follows : — 

(6.)  After  the  nerve  is  cleared  as  far 
as  the  spine,  clear  the  muscles  away  from 
the  femur,  and  divide  the  latter  about 
its  middle.  Divide  the  sciatic  nerve  as 
high  up  as  possible.  Pin  a  straw  flag  to 
the  toes  by  means  of  two  pins.  Fix  the 
femur  in  a  clamp  or  pair  of  muscle-forceps, 
supported  on  a  stand  (ficj.  108),  taking  care   Fia.  io8.--straw  Flag  attached 

■  v^t,,  ,  .^    '^.  "^         1      ^  rpi  to  a  Frog's  Leg  fixed  in  a 

that  the  gastrocnemms  is  upwards,     ihe        ciamp.  jv^.Nerve;  jp".  Flag, 
nerve  hangs  down,  and  must  be  manipu- 
lated with  a  camel's-hair  brush  dipped   in   normal  saline,  or  by 
means  of  a  hooked  glass  rod. 


l82  PRACTICAL  PHYSIOLOGY. 


[XXX.    I 


(c.)  Pinch  the  free  end  of  the  nerve  sharply  with  forceps;  the 
muscles  contract  and  the  straw  flag  is  suddenly  raised.  Cut  off 
the  dead  part  of  the  nerve,  contraction  also  occurs. 

(d.)  Prick  the  muscle  with  a  needle;  it  contracts. 

For  the  purposes  of  the  student  it  is  sufficient  to  expose  o  ie 
sciatic  nerve  in  sitUy  and  observe  the  movements  of  the  foot  an  1 
leg. 

Mechanical  stimulation  is  rarely  employed,  as  the  part  stimulated  is  apt  to 

be  injured  by  the  stimuli.  Heidenhain  in  1856  devised  what  he  called  a 
Tetanomotor  for  this  purpose.  It  consisted  of  a  Wagner  or  Neef  s  hammer, 
with  one  end  prolonged  and  carrying  a  small  ivory  hammer,  which  beat  the 
nerve  placed  under  it.  Recently  v.  UexkiiU  has  devised  apparatus  for  this 
purpose  [Zeits.  f.  Biol.,  Bd.  xxxi.). 

{e.)  Mechanical  Stimulation  by  removal  of  pressure. — Place  the  nerve  of  a 
nerve-muscle  preparation  on  a  moist  glass  plate,  press  the  nerve  slowly  and 
steadily  with  a  curved  i  mm.  thick  glass  hook.  If  pressure  be  applied 
steadily  and  uniformly  the  nerve  is  not  excited,  but  on  suddenly  removing 
the  pressure  the  muscle  contracts  {v.  UexkiiU). 

5.  Thermal  Stimulation. 

(a.)  To  the  same  preparation  apply,  either  to  muscle  or  nerve, 
a  wire  or  needle  heated  to  a  dull  heat ;  a  contraction  results  in 
either  case.     Cut  off  the  dead  part  of  the  nerve. 

6.  Chemical  Stimulation. 

(a.)  Place  saturated  solution  of  common  salt  in  a  glass  thimble, 
or  on  a  glass  sUde,  and  allow  the  free  end  of  the  nerve  to  dip 
into  it.  Owing  to  the  high  specific  gravity  of  the  saline  solution, 
the  nerve  floats  on  the  surface,  but  sufficient  salt  difi'uses  into 
the  nerve  to  stimulate  it.  After  a  few  moments,  the  joints  of 
the  toes  twitch,  and  by-and-by  the  whole  Hmb  is  thrown  into 
irregular,  flickering  spasms,  which  terminate  in  a  more  or  less 
continuous  contraction,  constituting  tetanus.  Cut  off  the  part 
of  the  nerve  aff'ected  by  the  salt ;  the  spasms-  cease.  Some  apply 
finely  powdered  salt  to  the  nerve,  others  glycerin. 

(h.)  Using  a  similar  preparation,  cover  the  leg  with  the  skin  of 
the  frog,  or  wrap  it  in  blotting-paper  saturated  with  normal  salLue. 
Expose  the  fresh-cut  end  of  the  nerve  to  the  vapour  of  strong 
ammonia.  The  ammonia  must  not  act  directly  on  muscle,  hence 
the  glass  vessel  must  be  placed  above  the  nerve,  and  the  nerve 
raised  to  the  ammonia.  There  is  no  contraction  of  the  muscle,  but 
the  ammonia  kilk  the  nerve. 

Instead  of  doing  this,  the  whole  leg  may  be  laid  on  a  card,  covered  with 
blotting-paper  moistened  with  normal  saline,  with  a  hole  in  it  just  suflSeient 
to  allow  the  sciatic  nerve  to  pass  through  it.  The  card  is  placed  over  a 
test-tube  containing  a  drop  of  ammonia  ;  the  nerve  hanging  in  the  vapour 
of  the  latter  is  speedily  killed,  but  there  is  no  contraction  of  the  muscle. 
Apply  ammonia  to  the  muscle  ;  it  contracts. 


XXXI.] 


ELECTRICAL   STIMULATION. 


183 


Note  that  although  ammonia  applied  directly  to  a  motor  nerve  does  not 
cause  contraction  of  the  corresponding  muscle,  yet  when  it  is  apj)lied  to 
the  central  end  of  the  divided  vagus  of  a  rabbit  it  causes  marked  reflex 
movements  of  the  respiratory  muscles. 

7.  Drjriiig. — If  the  nerve  be  allowed  to  hang  freely  in  the  air 
for  some  time,  it  gradually  dies,  and  the  muscles  twitch  irregularly, 
as  when  a  nerve  is  stimulated  chemically.  Moisten  the  nerve 
with  normal  saline  and  the  twitching  maij  cease.  It  may  be 
that  glycerin  acts  as  a  stimulus  through  absorbing  water. 


LESSON  XXXI. 


SINGLE  AND  INTERRUPTED  INDUCTION  SHOCKS 
—TETANUS -CONSTANT  CURRENT. 

1.  Electrical  Stimulation — Single  Induction  Shocks. — Appa- 
ratus.—Daniell's  cell,  induction  machine,  two  Du  Bois  keys  (or 
one  spring  key  or  mercury  key  and  one  Du  Bois  key),  five  wires, 
electrodes. 

(a.)  Arrange  a  cell  and  induction  machine  for  single  induction 
shocks  as  in  fig.  109.     A  spring  contact-key  or  Hg-key  is  more 


FlO.  109.— Scheme  for  Single  Induction  Shocks.    B.  Battery  ;  E,  IT.  Keys ;  P.  Primary, 
and  S.  Secondary  coil  of  the  induction  machine  ;  N.  Nerve ;  M.  Muscle. 

convenient  in  the  primary  circuit.  Electrodes  are  fixed*  to  the 
short-circuiting  key  (K')  in  the  secondary  circuit,  and  over  them 
the  nerve  is  to  be  placed. 

{h.)  Expose  the  sciatic  nerve  in  a  pithed  frog,  place  it  on  electrodes 
—preferably  a  pair  fixed  in  ebonite,  and  so  shielded  that  only 
one  surface  of  their  platinum  terminals  is  exposed  under  it.  Ur 
use  the  simple  shielded  electrodes  described  in  Lesion  XXVII.  6. 
Pull  the  secondary  coil  (S)  far  away  from  the  primary  (P),  raise 
the  short-circuiting  key  (K'),  make  and  break  the  primary  circuit 


1 84 


PRACTICAL  PHYSIOLOGY. 


[XXXL 


by  means  of  the  key  (K).  At  first  there  may  be  no  contraction, 
but  on  approximating  the  secondary  to  the  primary  coil  a  single 
muscular  contraction  %nll  be  obtained,  first  with  the  break  shock, 
and  on  approaching  the  secondary  nearer  to  the  primary  coil,  also 
with  the  make.  The  one  is  called  a  make  and  the  other  a  break 
contraction.  Enter  in  a  note-book  the  results  obtained.  N.B. — In 
all  cases  the  student  should  keep  an  account  of  the  experiment, 
and  especially  of  all  numerical  data  connected  therewith,  e.g, : — 


Single  make  and  break  shocks — Du  Bois  indudorium  with 
I  Daniell. 


Wstance  of  Primary  from 

Secondarv  Circuit 

in  cm. 

Begponseat 
Make(M). 

Response  at  Break 
(B). 

45 

O 

o 

44 

o 

Min.  twitch. 

43 

o 

Slight      „ 

4* 

o 

Stronger  „ 

41 

o 

>>         »f 

20 

o 

Max.        „ 

:i 

SUght  twitch. 

>»            *» 

Max.        „ 

ff           f» 

Compare  Ordinary  with  Helmholtz  Arrangement,  and  tabulate 
the  results  as  follows,  to  show  the  distance  of  the  secondary  coil 
at  which  mechanical  response  first  occurs. 


Ordinary  Du  Bois- 
Eeymond  CoiL 

With  Helmholtx't 
Modification. 

Nerve  make, .         , 
„     break, 

The  same  may  be  done  by  applying  the  electrodes  directly  to  the 
gastrocnemius  muscle,  i.e.,  direct  stimulation,  that  through  the 
nerve  being  indirect  stimulation. 


Ordinary  Du  Boia- 
Eeymond  CoiL 

With  Helraholtz's 
Modification. 

Muscle  make,         • 
„      break,         . 

XXXI.]  ELECTRICAL   STIMULATION.  1 85 

2.  Interrupted  Current  or  Repeated  Shocks. 

(a.)  Arrange  the  induction  machine  so  as  to  cause  Neef  s  hammer 
to  vibrate  as  directed  in  Lesson  XXVIII.  2.  On  applying  the 
electrodes  to  the  sciatic  nerve  or  gaetrocnemius  muscle,  at  once 
the  muscle  is  thrown  into  a  state  of  rigid  spasm  or  continuous 
contraction,  called  tetanus,  this  condition  lasting  as  long  as  the 
nerve  or  muscle  is  stimulated,  or  until  exhaustion  occurs. 

3.  Constant  Current. —Apparatus. — Daniell's  cells,  Du  Bois 
key  (or,  preferably,  a  simple  make  and  break  key),  four  wires, 
electrodes,  forceps,  and  nerve-muscle  preparation,  or  simply  expose 
the  sciatic  nerve  in  situ. 

(a.)  Use  two  .Daniell's  cells.     If  two  or  more  Daniell's  cells  be 
used,  always  connect  them  in  series,  i.e.,  the    +    pole  of  one  cell 
with  the  -  pole  of  the  next.     Connect  two  wires,  as  in  fig.  no, 
to  the  free  +   and  -  poles  of  the  battery 
B,    and  introduce  a  Du  Bois   key  (K')  to 
short-circuit   the   battery  circuit.     Fix  two 
shielded    electrodes   in    the   other  binding- 
screws  of  the   Du   Bois   key,    and   having 
prepared    a   nerve-muscle    preparation,    lay 
the  divided  sciatic  nerve  (N)  across  them, 
as   shown   in  fig.   no.       A    simple  key  to 
make  or   break    the    current   is    preferable 
to  the  short-circuiting   key,    as   the   latter 
allows  polarisation  currents  to  pass  when  it 

is    closed.  ^iq.    no.-Scheme   of   Cou- 

(h.)  Make  and  break  the  current,  and  a      stant current,  i^. Battery; 

•       ,'  1  1.         .•  i      -i    1      •  li'.    Short-cuciiitiiig    key; 

Smgle   muscular   contraction    or   twitch    is        JV.  Nerve;  J/.  Muscle. 

obtained,  either  at  making  or  breaking,  or 

both  at  making  and  breaking.     Notice  that  if  the  key  be  raised 

to  allow  the  current  to  flow  continuously  through  the  nerve,  no 

contraction  occurs,  provided  there  be  no  variation  in  the  intensity 

of  the  current.     The  electrodes  may  also  be  applied  to  the  muscle 

directly. 

(c.)  Rapidly  make  and  break  the  current  by  opening  and 
closing  the  key ;  a  more  or  less  perfect  Manns  is  produced.  ' 

{(l.)  If  it  be  desired  to  test  the  effect  of  a  constant  current  on 
muscle  alone,  then  the  terminations  of  the  motor  nerves  in  the 
muscle  must  have  been  paralysed  previously  by  curare,  so  that 
in  this  case  the  electrodes  must  be  applied  directly  to  the 
muscle. 

4.  Muscle  on  Mercury. — Lay  the  muscle  of  a  nerve-muscle 
preparation  on  the  surface  of  mercury.     Stimulate  the  nerve,  tha 


S6 


PRACTICAL   PHYSIOLOGY. 


[XXXI 


muscle  contracts,  but  does  not  elongate 
to  elongate  luiless  it  be  weighted. 


it  shows  little  tendency 


5.  Dead  Muscle  and  Nerve. — Immerse  a  nerve-muscle  preparation  for  a 
few  minutes  in  water  at  40°  C.  Both  are  killed,  and  none  of  the  above 
stimuli  cause  contraction. 

6.  The  Sartorins. — One  gets  a  clear  idea  of  the  shortening  and  thickening 
which  occur  when  a  muscle  contracts  by  using  the  sartorius,  as  its  fibres  are 
arranged  in  a  parallel  manner. 

(a.)  Pith  a  frog,  lay  it  on  its  back,  and  dissect  off  the  long  narrow  sartorius 
fi-om  the  inner  side  of  the  thigh.  The  thin  narrow  sartorius  (fig.  in) 
stretching  from  the  ilium  to  the  tibia  is  best  seen  if  it  be  moistened  with 
blood,  which  ditferentiates  its  edges.  To  isolate 
the  sartorius  the  best  way  is  to  cut  the  other 
parts  away  from  it.  Raise  its  tibial  tendon,  and 
round  it  tie  a  fine  silk  thread.  Gradually  raise 
the  muscle  by  means  of  the  thread,  and  with  fine 
scissors  cut  it  free  from  its  fascial  connections 
right  up  to  the  ilium.  Cut  it  out  with  the  ilium 
attached.  Its  nerve  enters  it  on  its  under  surface 
about  the  middle  of  the  muscle.  When  it  is 
divided  the  muscle  contracts.  Stretch  it  on  a 
slip  of  glass  or  hang  it  up  by  its  ilium  bony 
attachment  in  a  clamp. 

(6.)  Stimulate  the  muscle  first  at  its  ends  and 
afterwards  at  its  centre  or  equator,  as  in  Lesson 
XXXI.  1,  2,  with  (i.).  a  single  induction  shock, 
and  (ii.),  aftenvards  with  an  interrupted  current. 
Observe  the  shortening  and  thickening,  which 
are  much  greater  in  (ii.)  than  (i.).  The  muscle 
may  be  extended  again,  and  stimulated  as 
frequently  as  desired,  if  it  be  kept  moist. 

Fig.  hi.— Muscles  of  the  Left       7.  Unipolar  Stimulation. — Apparatus. 

t'i?i;ront.^^pS?e!:?ps;a"   -Baniell's   cell,   induction   machine,    Du 
s.  Sartorius ;  ad'.  Ad<iuctor   Bois  kevs,  (muscle-chamber),  wires,   elec- 

longiis;  PI.  Vastus  internus.    2.      t 
(See  figs.  105  and  106.)  trocles. 

A.  (a.)  Expose  the  sciatic  nerve  of  a 
frog,  and  place  the  frog  on  a  dry  cork  plate,  or  glass,  or  block  of 
paraffin.  Arrange  an  induction  apparatus  for  faradisation  with  the 
electrodes  short-circuited,  and  placed  under  the  sciatic  nerve  clear 
of  all  adjoining  muscles.  Open  the  short-circuit  key  and  find  a 
strength  of  current  (secondary  coil  at  25-30  cm.)  which  on 
faradisation  gives  feeble  tetanus. 

(h.)  Disconnect  one  of  the  electrode  wires  from  the  preparation, 
so  that  only  one  terminal  is  m  connection  with  the  nerve.  There 
is  no  contraction  when  the  secondary  key  is  open.  Insulate  the 
preparation  by  placing  it  on  a  block  of  paraffin  or  on  a  dry 
beaker, 

(c.)  Try  to  find  the  distance  of  the  secondary  coil  (8-10  cm.) 


( 


XXXII.]  STIMULATION   OF  MUSCLE.  1 87 

at  which  no  response  is  obtained  with  unipolar  stimulation,  but  a 
response  is  obtained  when  the  preparation  is  touched  with  finger. 
Why  is  there  a  response?  Because  by  touching  the  preparation 
one  suddenly  diminishes  the  resistance  to  the  passage  of  the  induc- 
tion currents  to  earth. 

Or  B.  (a.)  Set  up  a  cell  and  induction  coil  with  electrodes  for 
single  shocks.  Disconnect  one  of  the  electrodes  of  the  secondary 
coil,  the  other  one  being  binder  the  sciatic  nerve  or  the  nerve  of  a 
nerve-muscle  preparation  which  is  insulated  on  a  glass  plate.  If 
the  frog  is  on  a  frog-plate  put  the  frog-plate  on  a  dry  beaker  to 
insulate  it.     No  contraction  occurs  at  make  or  break. 

(b.)  Connect  the  disconnected  electrode  to  a  gas-pipe  and  so  to 
the  earth.  Contraction  takes  place  at  make  or  break.  It  is  in  order 
to  avoid  unipolar  stimulation  that  the  Du  Bois  key  is  used  to 
short-circuit  the  secondary  circuit. 

Or  C,  {a. )  Connect  the  Daniell  to  the  primary  coil  of  the  induction  machine 
either  for  single  shocks  or  tetanus,  introducing  a  Du  Bois  key  in  the  circuit. 
Connect  one  wire  with  the  secondary  coil,  and  attach  it  to  one  of  the  bind- 
ing screws  on  the  platform  of  the  muscle-chamber,  to  which  the  nerve  electrodes 
are  attached.  See  that  the  battery  and  induction  machine  are  perfectly  insul- 
ated by  supporting  them  on  blocks  of  paraffin. 

(6.)  Prepare  a  nerve-muscle  preparation,  and  arrange  it  in  the  muscle- 
chamber  in  the  usual  way,  laying  the  nerve  over  the  electrodes.  One  of  the 
electrodes  will  therefore  be  connected  with  the  secondary  circuit. 

(c.)  Make  and  break  the  primary  circuit  ;  there  is  no  contraction. 

(d.)  Destroy  the  insulation  of  the  preparation  by  touching  the  muscle,  or 
what  does  better,  allow  the  brass  support  of  the  muscle  to  touch  a  piece  of 
moist  blotting-paper  on  the  inner  surface  of  the  glass  shade  of  the  chamber. 
Every  time  the  brass  binding  of  the  shade  is  touched,  or  the  brass  support 
itself,  the  muscle  contracts.  Touch  the  secondary  coil  and  contraction 
results. 


LESSON"  XXXII. 


RHB  DNOME— TELEPHONE  EXPERIMENT— DIRECT 
AND  INDIRECT  STIMULATION  OP  MUSCLE- 
RUPTURING  STRAIN  OF  TENDON— MUSCLE 
SOUND— DYNAMOMETERS. 

1.  Fleischl's  Rheonome  and  Law  of  Excitation. — This  instru- 
ment (fig.  112)  is  useful  for  showing  Du  Bois-Reymond's  law, 
that  it  is  not  the  absolute  intensity  of  a  galvanic  current  flowing 
through  a  nerve  which  excites  it,  but  the  rapidity  of  the  variations 
in  the  intensity  of  the  current  which  excite  a  motor  nerve.     It 


i88 


PRACTICAL  PHYSIOLOGY. 


[xxxn. 


Fig.  112.— Fleischl's 
Rheonoin. 


consists  of  a  square  ebonite  base,  with  a  grooved  circular  channel  in 
it,  and  two  binding  screws,  with  zinc  attached,  and  bent  over  so  as 
to  dip  into  the  groove,  which  is  filled  with  a  saturated  solution  of 
zinc  sulphate.  A  vertical  arm,  with  binding  screws  attached  to  two 
bent  strips  of  zinc,  moves  on  a  vertical 
support.  It  is  a  kind  of  revolving  rheo- 
chord. 

(a.)  Connect  two  or  three  Daiiiell's  cells 
(copper  to  zinc)  with  the  binding  screws 
A  and  B,  introducing  a  Du  Bois  key  in 
one  wire.  Attach  the  electrodes,  intro- 
ducing a  Du  Bois  key  to  short-circuit  them, 
to  the  binding  screws,  C  and  D.  Fill  the 
groove  with  a  saturated  solution  of  zinc 
sulphate. 

(b.)  Arrange  the  nerve  of  a  nerve-muscle  preparation  over  the 
electrodes,  or  simply  expose  the  sciatic  nerve  of  a  frog  in  situ.  Pass 
a  constant  current  through  the  nerve,  observing  the  usual  effects, 
viz.,  contraction  at  make  or  break,  or  both,  but  none  when  the 
current  is  passing.  Then  suddenly  rotate  the  handle  with  its  two 
zinc  arms ;  this  is  equivalent  to  a  sudden  variation  of  the  intensity 
of  the  current ;  the  current,  of  courae,  continuing  to  pass  all  the 
time.     The  muscle  suddenly  contracts. 

When  the  two  ends  of  the  zinc  arc  stand  as  in  the  fig.,  i.e.,  o])posite  C  and 
D,  then,  on  closing  the  current,  most  of  the  current  goes  through  the  zinc  arc 
to  the  jneparation,  and  only  a  small  part  through  the  zinc  su]})hate  solution 
from  C  to  D.'  Thus  the  muscle  contracts  according  to  the  direction  and 
intensity  of  the  current,  either  on  closing  or  opening  the  key,  or  at  both. 
Turn  the  handle  so  that  the  zinc  arc  is  vertical  to  a  line  joining  C  and  D. 
There  is  no  current,  so  that  the  preparation  does  not  respond  either  on  closing 
or  opening. 

If,  while  the  zinc  arc  is  in  this  position,  the  circuit  be  closed,  and  the  zinc  arc 
suddenly  rotated  into  the  position  of  the  line  C,  D,  the  muscle  contracts, 
provided  in  the  first  experiment  a  closing,  i.e.,  make,  contraction  was  obtained. 
If  it  be  rotated  slowly  then  there  is  no  response.  Thus  one  can  allow  the 
current  to  glide  or  slide  into  the  nerve  {^^ eiiischleiclien")  without  causing 
excitation. 


2.  Direct  and  Indirect  Stimulation  of  Muscle. — When  the 
stimulus  is  applied  directly  to  the  muscle  itself,  we  have  direct 
stimulation ;  but  when  it  is  applied  to  the  nerve,  and  the  muscle 
contracts,  this  is  indirect  stimulation  of  the  muscle. 

(i.)  Induced  Current. — {a.)  Arrange  a  nerve-muscle  preparation, 
and  an  induction  machine  for  single  or  repeated  shocks  (Lesson 
XXXI.  1). 

(5.)  Test  first  the  strength  of  current- as  measured  by  the 
distance  between  the  secondary  and  primary  coils — which  causes 


XXXII.]  STIMULATION   OF  MUSCLE.  1 89 

the  muscle  to  contract  when  the  stimulus  is  applied  to  the  nerve, 
i.e.,  for  indirect  stimulation. 

{(',.)  Then  with  the  secondary  still  at  the  same  distance  from 
the  primary,  try  if  a  contraction  is  obtained  on  stimulating  the 
muscle  directly.  It  will  not  contract;  but  make  the  current 
stronger,  and  it  will  do  so.  The  excitability  of  muscle  to  direct 
stimulation  is  best  done  after  the  nerve-terminations  have  been 
paralysed  by  curare  (Lesson  XXXIII.). 

(ii.)  Constant  Current. — Connect  the  electrodes  with  two  Daniell's 
cells,  placing  a  Hg-key  in  the  circuit.  Place  the  electrodes  under 
the  nerve.  Contraction  occurs  at  make  only,  and  at  break  only 
if  the  preparation  is  very  excitable,  but  there  is  no  contraction 
when  the  current  is  passing  through  the  nerve. 


ADDITIONAL  EXERCISES. 

3.  Muscle  Sound. 

{a.)  Insert  the  tips  of  the  index-fingers  into  the  auditory  meatuses,  forcibly 
contracting  the  biceps  muscles.     A  low  rumbling  sound  is  heard. 

(6. )  When  all  is  still  at  night,  firmly  close  the  jaws,  and,  especially  if  the 
ears  be  stopped,  the  sound  is  heard. 

4.  Telephone  Experiment, 

{a.)  Arrange  a  nerve-muscle  preparation  with  its  nerve  over  a  pair  of 
electrodes.  Connect  the  latter  with  a  short-circuiting  Du  Bois  key.  To  the 
key  attach  the  two  wires  from  a  telephone. 

{b.)  Open  the  short-circuiting  key;  shout  into  the  telephone,  and  observe 
that  on  doing  so  the  muscle  contracts  vigorously. 

5.  Rupturing  Strain  of  Muscle  and  Tendon. 

{a.)  Dissect  out  the  femur  and  gastrocnemius  with  the  tendo  Achillis  of  a 
frog.  Fix  the  femur  in  a  strong  clamp  on  a  stand,  preferably  one  with  a 
heavy  base.  To  the  tendo  Achillis  tie  a  short  stout  thread,  and  hang  a  scale- 
pan  on  to  it. 

(6.)  Place  weights  in  the  scale-pan,  and  note  the. weight  required  to  rupture 
the  tendon  or  muscle.  Usually  the  mnscle  is  broken.  The  weight  added  will 
be  I  kilo.,  more  or  less,  according  to  tlie  size  of  the  frog. 

(c.)  Compare  the  rupturing  strain  of  a  frog's  gastrocnemius  which  has  been 
dead  for  forty-eight  hours.     A  much  less  weight  is  required. 

6.  Dynamometers. 

[a.)  Hand. — Test  the  force  exerted  first  by  the  right  hand  and  then  by  the 
left,  by  means  of  Salter's  dynamometer. 

{b.)  Arm. — Using  one  of  Salter's  dynamometers,  test  the  strength  of  the 
arm  when  exerted  in  pulling,  as  an  archer  does  when  drawing  a  bow. 


T90  PRACTICAL  PHYSIOLOGY.  [XXXIIL 


LESSON  XXXIII. 

INDEPENDENT  MUSCULAR  EXCITABILITY  —  AC- 
TION OF  CURARE— ROSENTHAL'S  MODIFICA- 
TION—POHL'S  COMMUTATOR. 

1.  Independent  Muscular  Excitability  and  the  Action  of 
Ciu'are. — Curare  paralyses  the  intramuscular  terminations  of  the 
motor  nerves. — Apparatus. — Daniell's  cell,  induction  machine, 
two  keys,  five  wires,  shielded  electrodes,  scissors,  fine-pointed 
forceps,  fine  aneurism-needle,  or  fine  sewing-needle  fixed  in  a 
handle,  with  the  eye  free  to  serve  as  an  aneurism-needle,  fine 
threads,  pithing-needle,  i  per  cent,  watery  solution  of  curare, 
hypodermic  syringe  or  glass  pipette. 

(a.)  Arrange  the  battery  and  induction  machine  for  an  inter- 
rupted current  with  a  key  in  the  primary  circuit,  and '  a  Du  Bois 
key  to  short-circuit  the  secondary,  as  in  Lesson  XXXI.  2. 

(/>.)  Destroy  the  brain  of  a  frog,  and  by  means  of  a  hypodermic 
syringe  or  a  fine  glass  pipette  inject  into  the  ventral  or  dorsal 
lymph-sac  two  drops  of  a  i  p.c.  watery  solution  of  curare.  [The 
curare  of  commerce  is  only  partly  soluble  in  water,  but  its  active 
constituent  curarin  is.  Rub  up  i  gram  curare  in  loo  cc.  water 
and  filter].  The  poison  is  rapidly  absorbed.  At  first  the  frog 
draws  up  its  legs,  in  a  few  minutes  it  ceases  to  do  so,  and  will  he 
in  any  position  in  which  it  is  put,  while  the  legs  are  not  drawn  up 
on  being  pinched,  and  the  animal  lies  flaccid  and  paralysed. 

(c.)  Expose  the  heart,  and  observe  that  it  is  still  beating. 

{(I.)  Expose  one  sciatic  nerve. 

(i.)  Stimulate  the  sciatic  nerve  with  interrupted  shocks  (faradisa- 
tion) ;  there  is  no  contraction. 

(ii.)  Apply  the  electrodes  to  the  muscles  ;  they  contract. 

Therefore  curare  ha^ paralysed  some  part  of  the  motor  nerves,  hit 
not  the  muscles. 

In  curare  poisoning  the  nerve-trunk  itself  is  not  inexcitable,  but 
the  nerve-endings  in  the  skeletal  muscles  are  so  afi'ected,  i.e., 
paralysed,  as  to  prevent  the  excitatory  state  of  tlie  nerve  being 
propagated  from  the  nerve  to  the  muscle.  The  following  experi- 
ment proves  this : — 

2.  On  what  Part  of  the  Motor  Nerve  does  Curare  Act  ? 
{a.)  Induction  apparatus  as  in  the  previous  experiment. 

(h.)  Destroy  the  brain  of  a  frog.  Expose  the  sciatic  nerve  and 
the  accompanying  artery  and  vein  on  one  side,  e.g.,  the  Z^/V,  taking 
great  care   not   to   injure   the   blood-vessels.     Isolate   the   sciatic 


XXXIII.]      INDEPENDENT  MUSCULAR  EXCITABILITY.  I91 

nerve,  and  then  tie  a  stout  ligature  round  all  the  other  structure.^ 
of  the  thigh.  In  this  way  none  of  the  poison  can  pass  by  a  col 
lateral  circulation  into  the  parts  below  the  ligature. 

(r.)  Inject  a  few  drops  of  a  i  p.  c.  solution  of  curare  into  the 
ventral  lymph-sac.  The  poison  will  be  carried  to  every  part  of  tlie 
body  except  the  left  leg  below  the  ligature.  The  animal  is  rapidly 
paralysed  (20-30  mins.),  but  if  the  non-poisoned  leg  (left)  is 
pinched,  it  is  drawn  up,  while  tlie  poisoned  leg  (right)  is  not,  i.r  , 
there  is  a  reflex  movement  of  the  non-poisoned  limb,  so  that  the 
afferent  (sensory)  nerves,  spinal  centre  and  motor  nerves  are  still 
unaffected. 

(d.)  Wait  until  the  animal  is  thoroughly  under  the  influence  of 
the  poison,  i.e.,  when  all  reflexes  cease,  and  then  expose  both  sciatic 
verves  as  far  up  as  the  vertebral  column  and  as  far  down  as  the 
knee, 

(i.)  Stimulate  the  right  sciatic  nerve.  There  is  no  contraction. 
Therefore  the  poison  has  acted  either  on  nerve  or  muscle. 

(ii.)  Stimulate  the  rigJit  gastrocnemius  muscle;  it  contracts. 
Therefore  the  poison  has  acted  on  some  part  of  the  nervous  path, 
but  not  on  the  muscle. 

(iii.)  Stimulate  the  left  sciatic  above  the  ligature;  the  left  leg 
contracts.  The  part  of  the  nerve  above  the  ligature  was  supplied 
with  poisoned  blood,  so  that  the  nerve-trunk  itself  is  not  paralysed, 
as  may  be  proved  by  stimulating  any  part  of  the  left  sciatic  as  far 
down  as  its  entrance  into  the  gastrocnemius.  Stimulating  any 
part  of  the  left  nerve  causes  contraction.  Therefore  neither 
nerve-trunk  nor  muscle  is  affected.  The  nerve-impulse  is  blocked 
somewhere,  in  all  probability  by  paralysis  of  the  terminations  of 
the  motor  nerves  within  the  muscle. 

(e.)  Apply  several  drops  of  a  strong  solution  of  curare  to  the  left 
gastrocnemius,  and  after  a  time  stimulate  the  left  sciatic  nerve ; 
there  is  no  contraction,  but  on  stimulating  the  muscle  itself  con- 
traction takes  place. 

The  independent  excitability  of  muscle  is  further  proved  by 
other  experiments,  all  of  which  we  owe  to  W.  Kiiline. 

(i)  The  Sartorius  experiment  (p.  191). 

(2)  Kiihne's  Curare  experiment  (p.  194). 

(3)  The  Gracilis  experiment  (Lesson  L.). 

3.  Kiihne's  Sartorius  Experiment. 

{a.)  Isolate  the  sartorius  (fig.  iii)  by  the  method  given  at 
p.  186.  Suspend  the  muscle  by  the  thread  tied  around  its  tibial 
attachments,  i.e.,  with  its  ihac  end  downwards. 

{b.)  Allow  the  ihac  end  to  dip  into  a  drop  of  pure  glycerin 
placed  on  a  greasy  surface.     The  muscle  gives  no  response.     Why  1 


192 


PRACTICAL  PHYSIOLOGY. 


[XXXIII 


Because  it  is  devoid  of  nerve-fibres.  Then  cut  across  the  muscle 
about  4  mm.  higher  up  and  dip  tlie  fresh  -transverse  section  into 
the  glycerin.  Soon  the  muscle  twitches.  Why?  As  glycerin 
stimulates  nerve  and  not  muscle,  there  is  no  response  until  the 
glycerin  is  eitlier  directly  applied  to  nerve-fibres,  or  is  diffused 
so  as  to  aftect  them. 

Klihne  used  this  experiment  to  demonstrate  the  independent 
excitability  of  muscle  and  nerve. 

4.  Comparative  Excitability  of  Muscle  and  Nerve. 

(a.)  Prepare  a  frog  as  for  the  curare  experiment,  i.e.,  ligature 
one  leg  all  except  the  sciatic  nerve  on  that  side,  then  inject  curare 
into  a  lymph-sac.  After  the  curare  has  acted,  expose  both  sciatic 
nerves  and  both  gastrocnemius  muscles. 

(b.)  ^N'ote  the  approximation  of  the  secondary  coil  to  the  primary 
required  to  obtain  a  mechanical  response  or  contraction  to — 
(i.)  Single  make  induction  shocks, 
(ii.)  Single  break  induction  shocks, 
(iii.)  Faradisation. 

"When  the  electrodes  are  applied  to  the  sciatic  nerve  of  the 
ligatured  limb,  i.e.,  the  protected  side,  tabulate  the  results. 

(c.)  Apply  the  electrodes  directly  to  the  gastrocnemius  muscle 
of  the  opposite  side,  i.e.,  the  poisoned  limb,  which  is  practically 
nerveless,  as  curare  paralyses  the  terminations  of  the  motor  nerves. 
It  will  be  found  that  a  stronger  shock  is  required  to  cause  the 
muscle  to  contract  than  is  necessary  through  the  intervention  of 
the  nerve,  i.e.,  muscle  is  less  excitable  than  nerve. 


Direct  Stimulation  of 
Nerveless  Muscle. 

Distance  of  Primary  from 
Secondary  Coil  in  cm. 

Stimulation  of  Nerve  of 
Ligatured  Limb. 

M. 

B. 

M. 

B. 

0 
0 
0 

0 

0 

c 
c 
c 

22 
21 
20 
19 

30 
29 

28 
27 

0 
0 
0 

0 

c 

C 
0 

c 

Faradisation. 


Nerveless  Muscle. 

Distance  of  P  from  S. 

Ligatured  Limb. 

0 
0 
0 

0 

35 
34 
33 
32 

0 
0 
0 
0 

XXXIII.]      INDEPENDENT   MUSCULAR   EXCITABILITY.  I93 

5.  Pohl's  Commutator  (fig.  113)  is  used  for  sending  a  current 
along  two  different  pairs  of  wires,  or  for  reversing  the  direction  of 
the  current  in  a  pair  of  wires.  It  consists  of  a  round  or  square 
wooden  or  ebonite  block  with  six  cups,  each 
in  connection  with  a  binding  screw.  Between 
two  of  these  stretches  a  bridge  insulated  in 
the  middle.  The  battery  wires  are  always 
attached  to  the  cups  connected  with  this 
(i  and  2).  When  it  is  used  to  pass  a  current 
through  different  wires,  the  cross-bars  are 
removed  and  wires  are  attached  to  all  six  cups,  Tator^with^CroM-bars.'" 
3  and  4,  5  and  6.  On  turning  the  bridge 
to  one  side  or  other,  the  current  is  sent  through  one  or  other  pair 
of  wires.  To  reverse  the  direction  of  a  current,  only  one  pair  of 
wires,  besides  the  battery  wires,  is  attached  to  the  mercury  cups, 
e.g.,  10  3  and  4,  or  5  and  6,  the  cross-bars  remaining  in. 


ADDITIONAL  EXERCISES. 

6.  Curare  and  Rosenthal's  Modification. 

{a.)  Prepare  a  frog  as  in  the  previous  experiment,  ligature  the  lefb  leg— all 
except  the  sciatic  nerve— and  inject  curare.  After  complete  paralysis  occurs, 
dissect  out  both  legs  with  the  nerves  attached.  Attach  straw  flags  (NP  and  P) 
of  different  colours  to  the  toes  of  both  legs  by  pins,  and  fix  both  femora  in 
muscle-forceps  (F)  with  the  gastrocnemii  uppermost  (fig,  114).  Place  the 
nerves  (N)  on  the  platinum  points  of  Du  Bois-Reymond's  electrodes  (fig.  98). 

{h.)  Arrange  the  induction  apparatus  as  in  fig.  114,  connecting  the 
terminals  of  the  secondary  coil  with  the  piers  of  a  Pohl's  commutator  (fig.  113) 
without  cross-bars  (H).  Two  other  wires  pass  from  two  other  binding  screws 
of  the  commutator  to  the  electrodes  (N),  while  two  thin  wires  pass  from  the 
other  two  binding  screws  (C),  and  their  other  ends  are  pushed  through  the 
gastrocnemii  muscles.  The  commutator  enables  the  tetanising  currents  to  be 
passed  either  through  both  nerves  or  both  muscles.  It  is  more  convenient 
if  the  secondary  circuit  have  a  key,  so  that  it  may  be  short-circuited  when 
desired. 

(i.)  Set  Neef's  hammer  going,  and  turn  the  handle  of  the  commutator  so 
that  the  current  passes  through  both  nerves  ;  only  the  non-poisoned  leg  (NP) 
contracts. 

(ii.)  Reverse  the  handle  and  pass  the  current  through  both  muscles  ;  both 
contract. 

(iii.)  Rosenthal's  Modification.— Push  the  secondary  spiral  faraway  from 
the  primary,  and  pass  the  current  through  both  muscles.  At  first,  if  the  coils 
be  suflBciently  far  apart,  there  is  no  contraction  in  either  muscle.  Gradually 
push  up  the  secondary  coil,  and  notice  on  doing  so  that  the  non-poisoned 
limb  contracts  first,  and  that,  on  continuing  to  push  up  the  secondary  coil, 
both  muscles  ultimately  contract. 

7,  Action  of  Curare— Bernard's  Method. — Prepare  two  nerve-muscle  pre- 
parations, and  dip  the  nerve  of  one  (A)  and  the  muscle  of  the  other  (B)  into  a 


194 


PRACTICAL  PHYSIOLOGY. 


[XXXIV. 


soli.tion  of  curare  in  two  watch-glasses.     On  stimulating  the  nerve  of  A,  its 
muscle  contracts  ;  on  slimulatiiig  the  nerve  of  B,  its  muscle  does  not  contract, 

but  the  muscle  contracts  when  it  is 
stimulated  directly.  In  A,  although 
the  poison  is  applied  directly  to  the 
nerve-trunk,  the  nerve  is  not  para- 


I  '^  t 


[4.— Scheme  of  the  Curare  Experiment. 
Battery;  /.  Primary,  11.  Secondary 
spiral ;  N.  Nerves  ;  F.  Clamp ;  NP.  Non- 
poisoned  leg;  P.  Poisoned  leg;  C.  Com- 
mutator; K.  Key.  Tlie  short-circuiting 
key  in  the  secondary  ciixuit  is  omitted  in 
the  diagram. 


8.  Euhne*8  Curare  Experiment. 

—(a.)  To  the  margin  of  a  meat- plate 
fix  two  copper  slips,  to  serve  as 
attachments  for  the  electrodes,  and 
between  the  copper  terminals  place 
a  strip  of  filter-paper  moistened  with 
normal  saline. 

{b.)  Excise  the  sartorius  of  a  large 
frog,  and  cut  it  transversely  into 
five  pieces  of  nearly  equal  length. 
Plade  them  in  their  original  order 
on  the  filter-paper,  numbering  them 
I  to  5.  Pass  a  feeble  tetanising 
current  through  the  muscle,  and 
note  that  the  central  parts,  i.e.,  2, 
3,  and  4,  contract,  while  i  and  5 
remain  quiescent.  On  making  the 
current  stronger  the  terminal  parts 
also  contract.  Why  1  Because 
there  are  no  nerves  at  the  end  of 
the  sartorius.  and  in  the  first  instance 
the  muscular  fibres  are  really  excited 
by  stimulation  of  the  intramuscular 
terminations  of  the  nerves,  while  in 
the  case  of  the  end  parts  of  the 


divided  muscle  the  muscle  was  stimulated  directly. 

(c.)  If  a  curarised  sartorius  be  experimented  on  in  the  same  way  all  the 
parts  contract  at  once,  because  all  the  motor  nerves  in  the  muscle  are  para- 
lysed. 


LESSON  XXXIV. 


THE  GRAPHIC  METHOD-MOIST  CHAMBBR- 
SINQLE  CONTRACTION. 


1.  Recording  Apparatus. — Use  a  revolving  brass  cylinder  or 
other  moving  surface  covered  with  smoked  glazed  paper.  The 
velocity  of  the  moving  surface  is  usually  determined  by  recording 
simultaneously  the  vibrations  of  a  tuning-fork  of  known  rate  of 
vibration,  or  an  electro-magnetic  time-marker,  or  by  a  vibrating 
reed   (p.  211).     It   does   not  matter   particularly   what   form  of 


XXXIV.] 


THE   GRAPHIC   METHOD. 


195 


recording  drum  is  used,  provided  it  moves  smoothly  and  evenly, 
and  is  capable  of  being  made  to  move  at  different  speeds  as  required. 
In  Hawksley's  form  of  drum  this  is  accomplished  by  placing  the 
drum  on  different  axles,  moving  at  diff'erent  velocities.  In  Lud wig's 
form  (fig.  115)  this  is  done  by  moving  a  small  wheel,  71,  on  a  large 
brass  disc,  D.  Where  a  number  of  men  have  to  be  taught  at 
once,  one  must  have  recourse  to  an  arrangement  of  shafting, 
moved,  say,  by  a  water-motor  or  turbine,  from  which  several 
drums  can  be  driven  by  cords.  Or  one  may  use  a  small  gas- 
engine  as  the  motive  power,  and   cords  passing  over  pulleys  to 


iiillBiiiii^^ 


FlO.  115. — Liidwig's  Revolving  Cylinder,  R,  moved  by  the  clockwork  in  the  box  A,  and 
regulated  by  a  Foucault's  regulator  on  the  top  of  the  box.  The  disc  D,  moved  by 
the  clockwork,  presses  upon  the  wheel  n,  which  can  be  raised  or  lowered  by  the 
screw  L,  thus  altering  the  position  of  n  on  D,  so  as  to  cause  the  cylinder  to  rotate 
at  different  rates.  The  cylinder  Itself  can  be  raised  by  the  handle  U.  Ou  the  left 
side  of  tlie  figure  is  a  mercurial  manometer. 

move  the  drums.  This  is  the  arrangement  adopted  in  the  Physio- 
logical Department  of  Owens  College,  so  that  a  number  of  men 
can  work  at  the  same  time,  each  being  provided  with  recording 
apparatus  for  himself.  The  Thirlemere  water-motor  may  also 
be  used  for  actuating  a  number  of  recording  cylinders. 

2.  Fixing  and  Smoking  the  Paper. — The  paper  is  glazed  on 
one  surface,  and  is  cut  to  the  necessary  size  to  suit  the  drum. 
The  drum   can  be  removed  from  the  clockwork  or  other  motor 


196  PRACTICAL   PHYSIOLOGY.  [XXXIV. 

which  moves  it,  and  is  then  covered  with  a  strip  of  paper,  the 
latter  being  laid  on  evenly  to  avoid  folds,  glazed  side  outermost. 
One  edge  of  the  paper  is  gummed,  and  slightly  overlaps  the 
other  edge.  Leave  it  for  a  few  minutes  until  the  gum  dries.  The 
paper  has  then  to  be  blackened,  by  holding  the  drum  and  keeping 
it  moving  over  a  fan-tailed  or  bat's  wing  gas-burner,  or  paraffin 
lamp — the  former  is  preferable.  Take  care  that  the  soot  from 
the  flame  is  deposited  evenly  and  lightly,  and  see  that  it  is  not 
burned  into  the  paper.  The  drum  is  then  placed  in  position  in 
connection  with  its  motor.     (See  Appendix.) 

To  obtain  a  very  fine  film  of  soot,  Hlirthle  has  invented  a  "  smoke-spray." 
The  soot  from  the  flame  of  a  turpentine  lamp  is  blown  by  'means  of  an 
elastic  bail-bellows  against  the  paper. 

3.  General  Rules  for  Graphic  Experiments. 

(i.)  Arrange  the  apparatus  completely,  cover  the  drum  with 
paper,  and  smoke  it,  before  beginning  the  dissection. 

(2.)  Test  all  the  connections  stage  by  stage  as  they  are  made. 

(3.)  Each  tracing  is  to  be  inscribed  with  the  name  of  the 
individual  who  made  it,  the  date,  what  it  shows,  and  then  it 
is  varnished. 

4.  Myographs. — Various  forms  are  in  use,  but  most  of  them 
consist  of  a  light  lever  which  is  raised  by  the  contracting  muscle, 
and  so  arranged  as  to  record  its  movement  on  a  smoked  surface  of 
paper  or  glass.  Such  curves  are  called  "  isotonic  "  by  Pick.  The 
movements  of  the  muscle  are  thereby  magnified  and  rendered 
visible  to  the  eye.  Or  the  lever  may  record  its  movements  on  a 
moving  surface.  Taking  advantage  of  the  fact  that  a  muscle  when 
it  contracts  becomes  both  shorter  and  thicker,  myographs  have 
been  constructed  on  three  principles  : — 

(a)  Shortening  of  muscle  attached  to  a  lever. 
(/5)  Thickening  of  muscle  on  which  the  lever  rests. 
But  suppose  a  muscle  to  be  so  fixed  that  during  activity  it  cannot 
contract,  then  we  have  changes  »in  tension,  so  that  we  can  record 
changes  of  tension  bv  the  so-called  "isometric  "  method  introduced 
by  Fick  (Lesson  XXXVL). 

(y)  Changes  in  tension. 
The  recording  surface  on  wliich  the  style  of  the  lever  writes  may 
be— 

(i.)  Stationary  (PJlw/er^s). 
(2.)  Rotatory  (Helmholtz's). 
(3.)  Swinging  pendulum  (Fick^s). 

(4.)  Moved  from  side  to  side  by  a  spring,  either  vertically  (Du 
Bois~Reymo)id)  or  horizontally. 


XXXTV.] 


THE   OKAPHTC   WITHOD. 


197 


5.  Muscle-Lever  (change  in  length  of  muscle). — It  is  customary 
to  use  such  a  muscle-lever  as  is  shown  in  fig.  116,  with  the  weiglit 
attached  directly  under  the  point  of  attachment  of  the  muscle  to 
the  lever.  This  has  its  disadvantages,  as  it  is  set  into  vibration  by 
the  rapid  rise  of  the  lever.  Fick  has  shown  that  by  using  a  light 
straw  lever,  the  muscle  itself  being  made  tense  not  by  a  weight 
applied  directly  under  the  point  of  attachment  of  the  muscle  to 
the  lever,  but  by  attaching  the  weight  over  a  small  pulley  fixed 
to  the  steel  axis  to  which  the  lever  is  attached,  by  this  arrange- 
ment the  weight  is  raised  but  little,  and  even  with  a  rapid  con- 
traction does  not  move  quickly. 


Fig.  116.— Moist  Chamber.    N.  Glass  shade;  E.  Electrodes;  L.  Lever;  W.  Weight) 
TM.  Time-marker ;  other  letters  as  in  previous  figures. 


6.  Moist  Chamber  (fig.  116). — To  prevent  a  preparation  from 
getting  dry,  enclose  it  in  a  moist  chamber,  which  is  merely  a  glass 
shade  placed  over  the  preparation.  To  keep  the  air  and  the  pre- 
paration moist,  cover  the  sides  of  the  shade  with  blotting-paper 
moistened  with  normal  saline. 

7.  Varnish  for  Tracings. — ^The  tracing  is  drawn  through  the  varnish  and 
then  hung  up  to  dry. 

(a.)  A  good  varnish  consists  of  gum  mastic  or  white  shellac  dissolved  to 
saturation  in  methylated  spirit. 

(Ik)  Where  a  large  quantity  is  used,  and  economy  is  an  object,  gum  juniper 
may  be  used  instead  of  mastic. 

(c. )  Dissolve  4  oz.  of  sandarac  in  15  oz.  of  alcohol,  and  add  half  an  oz.  of 
chloroform,' 

8.  Single  Contraction  or  Twitch.— Apparatus. — Recording 
drum,  Daniell's  cell,  Hg-key,  induction  coil,  Du  Bois  key,  wires, 


198  PRACTICAL    PHYSIOLOGY.  [XXXIV. 

electrodes,  moih>t  chamber  and  lever  (or  crank-myograph),  moist 
blotting-paper,  stout  ligatures,  hook,  pins,  lead  weight  (20  grams). 

(a.)  Cover  the  drum  with  glazed  paper,  smoke  it,  and  arrange  it 
to  move  slowly. 

(h.)  Arrange  the  apparatus : — Daniell's  cell  and  a  mercury  key 
in  the  primary  circuit,  the  secondary  circuit  short-circuited,  and 
with  wires  going  to  the  binding  screws  on  tlie  platform  of  the 
moist  chamber  on  the  myograph  (fig.  116).  [The  muscle  may  be 
caused  to  contract  either  by  stimulating  it  directly,  in  which  case 
tlie  electrodes  are  made  of  thin  wires,  and  merely  pushed  through 
the  two  ends  of  the  gastrocnemius,  or  indii'ectly  through  the  nerve. 
It  is  convenient  to  use  the  latter  method  (Lesson  XXXII.).] 

(c.)  Make  a  nerve-muscle  preparation,  leaving  the  lower  end  of 
the  femur  in  connection  with  the  gastrocnemius,  and  cut  away  the 
tibia  and  fibula.  With  the  point  of  a  sharp  pair  of  small  scissors 
make  a  small  hole  in  the  tendo  Achillis,  and  insert  in  it  an  S-shaped 
hook,  made  by  bending  a  pin.  Arrange  the  preparation  in  the 
moist  chamber  by  fixing  the  femur  in  the  muscle  clamp,  and  by 
means  of  a  stout  thread  attach  the  hook  in  the  tendo  Achillis  to 
the  writing-lever.  See  that  the  muscle  or  ligature  goes  clear 
through  the  hole  in  the  stage,  and  that  the  hook  does  not  catch  on 
anything.  Place  the  nerve  over  the  electrodes,  and  cover  the  whole 
preparation  with  the  glass  shade  lined  on  three  sides  with  moist 
blotting-paper.  Load  the  lever  either  directly  or  by  means  of  a 
scale-pan  near  where  the  muscle  is  attached  to  it  by  a  weight  of 
about  20  grams,  and  make  the  lever  itself  write  horizontally  on  the 
cylinder.  The  writing-style  on  the  tip  of  tlie  lever  may  be  made 
of  very  thin  copper  foil  or  parchment  paper,  fastened  to  the  lever 
with  sealing-wax  or  telegraph  composition. 

As  here  arranged  the  primary  circuit  is  made  and  broken  by 
hand. 

According  as  the  recording  surface  is  stationary  or  moving 
when  the  muscle  contracts  and  raises  the  lever,  either  an  upward 
hue  or  a  curve  will  be  made  upon  the  paper.  In  the  latter  case 
the  form  of  the  curve  will  vary  with  the  velocity  of  the  drum. 

A.  Simple  twitch  with  the  recording  cylinder  stationary. 

By  this  arrangement  one  registers  only  the  lift  or  height  of  the 
contraction,  and  its  relation  to  the  strength  of  the  stimulus; 
yielding  minimal  and  maximal  contractions.  A  light  (isotonic) 
lever  is  chosen,  sucli  as  will  amplify  the  movement  6-S  times, 
while  the  weight  to  be  lifted  is  such  that  the  tension  of  the 
muscle  is  about  8-10  grams. 

(a.)  Push  the  secondary  coil  away  from  the  primary,  open  the 
key  in  the  secondary  circuit,  and  make  and  break  the  primary 


XXXIV.]  THE  GRAPHIC   METHOD.  199 

circuit.  There  may  be  no  contraction  at  either  M.  or  B.  Close 
the  secondary  circuit  key. 

(6.)  Open  the  short-circuiting  key,  gradually  push  up  the  secondary 
coil,  and  break  the  primary  circuit  by  means  of  the  key  in  it. 
Observe  when  the  first  feeble  single  contraction  or  twitch  is 
obtained  =  minimal  contraction.  Make  the  primary  circuit,  there 
is  no  contraction.  The  break  shock  is  drongur  than  the  make. 
Record  under  each  contraction  whether  it  is  a  make  (M.)  or  break 
(B.)  shock,  and  the  distance  in  centimetres  of  the  secondary  from 
the  primary  coil.  The  minimal  contraction  may  first  be  obtained 
when  the  secondary  coil  is  35-40  cm.  from  the  primary.  Move 
the  drum  a  short  distance  with  the  hand ;  the  lever  inscribes  a  base 
Une  or  abscissa. 

(c.)  Push  up  the  secondary  coil  .5  cm.  at  a  time.  Test  the  effect 
of  the  make  and  break  shocks,  after  each  test  moving  the  cylinder 
with  the  hand,  and  recording  the  result  as  to  M.  or  B.,  and  the 
distance  in  centimetres  of  the  secondary  from  the  primary  coil. 
After  a  time  a  'M.  contraction  appears,  and  on  pushing  up  the 
secondary  coil  the  M.  contraction  becomes  as  high  as  the  B. 
(fig.  117). 


FlO.  117.— Contractions  obtained  with  make  (M.)  and  break  (B.)  induction  shocks.  The 
numbers  indicate  the  distance  of  the  secondary  from  the  primary  coil.  The  cylinder 
is  stationary  during  each  contraction  and  Is  then  moved  a  little  distance  by  hand. 


{d.)  Increase  the  stimulus  by  bringing  the  secondary  nearer 
the  primary  coil,  and  notice  that  the  contractions  do  not  become 
higher  =  maximal  contraction.  In  each  case  keep  the  M.  and 
B.  contractions  obtained  with  each  strength  of  current  close 
together  Their  relative  heights  can  then  be  readily  compared 
(fig.  117). 


B.  Twitch  with  Cylinder  revolving  (fast  speed). — Arrange 
the  experiment  as  in  A,  but  allow  the  cylinder  to  revolve  about 
50  centimetres  per  second. 

(a. )  Select  a  strength  of  stimulus  (break  shock  only)  which  is 
known  to  cause  a  contraction,  and  while  the  cylinder  is  revolving, 
cause  the  muscle  to  contract. 


200  PRACTICAL   PHYSIOLOGY.  [XXXV. 

(/>.)  Study  the  muscle-curve  obtained,  a  so-called  "  isotonic " 
curve  (fig.  i2i). 

C.  Vary  the  velocity  of  the  cylinder,  and  observe  how  the 
form  of  the  curve  varies  with  the  variation  in  velocity  of  the 
cylinder   (fig.   ii8).      Use  only  the  break  shock,  and  record  the 

contractions  either  (i.) 
all  on  one  abscissa,  or 
(ii.)  record  each  con- 
traction on  a  different 
abscissa,  recording  a 
time-curve  imder  each 
(Lesson  XXXV.). 

D.  Remove  the  trac- 
■„     ,   o    .  •     c-     ,  .  0  V      o-    ,     ^gs  and  varnish  them. 

Fig    1 1 3— Fro?  s  Gastrocnemius  Stimulated  by  a  Single         ° 
Make  (M.)  and  Break  (B.)  Shock,  the  distance  between 

the  primary  and  secondary  coil  being  the  same  for  both  n     Ttelatlon      of 

shocks.  In  the  lower  figure  the  muscle  was  somewhat  *  «  ,       / 

fatigued.    Slow  rate  of  speed.  *'  Lilt      tO  Strength  01 

Stimulus.  —  Suppose 
one  uses  only  break  shocks,  and,  beginning  with  the  first  efi'ective 
stimulus  ("  Minimal  Contraction  ")  and  gradually  increasing  the 
strength  of  the  stimulus,  one  obtains  a  gradual  increase  in  the  height 
of  the  "  Hft "  until  a  certain  maximum  of  lift  ("  Maximal  Con- 
traction ")  is  reached,  above  which,  even  though  the  stimulus  be  in- 
creased, there  is  no  further  shortening  of  the  muscle.  If  a  muscle 
be  stimulated  directly  {i.e.,  the  electrodes  appUed  to  the  muscle 
direct),  the  difference  between  the  first  efifective  stimulus  (minimal) 
and  the  first  eSective  maximal  stimulus  is  considerably  greater  than 
by  indirect  stimulation  {i.e.,  when  the  stimulus  is  apphed  through 
the  nerve). 


LESSON  XXXV. 

CRANK-MYOGRAPH— AUTOMATIC  BREAK. 

Instead  of  the  muscle-lever  shown  in  fig.  1 16,  very  frequently  the 
crank-myograph  is  used  (fig.  1 1 9).  The  muscle  placed  on  it  can 
be  kept  moist  by  a  cover  of  blotting-paper  moistened  with  normal 
saline. 

1.  The  Crank-Myogi'aph  (fig.  119)  is  fixed  on  a  suitable  sup- 
port, so  that  it  can  be  adjusted  to  any  height  desired. 

After-Load. — In  the  crank-myograph,  under  the  lever,  is  a 
screw  on  which  the  horizontal  arm  of  tlie  bell-crank  rests  (fig.  119, 


XXXV.] 


CRANK-MYOGRAPH. 


201 


a),  so  that  the  muscle  is  loaded  only  during  its  contraction.  Thug 
a  muscle  may  be  '*  loaded  "  or  "  after-loaded  "  ;  in  the  former  case, 
the  muscle  is  loaded  with  a  weight,  both  when  it  is  at  rest  and 
when  contracting,  but  in  an  "  after-loaded "  muscle  the  muscle 
raises  the  ^veight  only  during  contraction,  and  is  not  stretched  by  it 
when  at  rest.  The  experiment  is  arranged  in  the  same  way  as  in 
Lesson  XXXIV.  8. 

(a.)  Make  a  preparation  of  the  gastrocnemius  with  the  lower  end 
of  the  femur  attached.  Pin  the  femur  firmly  to  the  cork  plate  of 
the  myograph  covered  with  blotting-paper  moistened  by  normal 
saline.  Tie  a  stout  ligature  round  the  tendo  Achillis,  by  a  hook  fix  the 
ligature  to  the  short  arm  of  the  lever,  add  a  weight  of  10-20  grams 
to  the  lever,  and  see  that  the  lever  itself  is  horizontal.  Thrust  two 
fine  wires — which  act  as  electrodes — from  the  Du  Bois  key  in 
the  secondary  circuit  through  the  upper  and  lower  end  of  the 
gastrocnemius  muscle. 


9lQ.  110.— Crank-Myograph,    TT,  W.  Block  of  wood ;  M.  Muscle ;  F.  Femur ;  P.  Pin  to 
fix  F;  L.  Lever ;  WT.  Weight ;  a.  Screw  for  after-load ;  C.  Cork  ;  B,  B.  Brass  box. 

(&.)  Arrange  the  style  of  the  lever  so  that  it  writes  on  the 
cylinder,  and  repeat,  if  desired,  the  experiments  of  the  previous 
Lesson. 

(c.)  Use  different  weights — 5 — 20 — 50  grams — and  observe  how 
the  form  of  the  curve  varies  on  increasing  the  weight  attached  to 
the  lever. 


2.  Automatic  Break,  t>.,  Method  of  Excitation. — It  is  con- 
venient to  use  a  single  break  induction  shock,  i.e.,  the  secondary 
coil  is  at  such  a  distance  from  the  primary  that  only  the  break  shock 
is  effective.  One  may,  of  course,  break  the  primary  circuit  by  the 
hand,  as  in  the  previous  experiments,  but  this  is  not  convenient 
It  is  better  to  have  an  "automatic  break"  (fig.  120)  done  by  the 
drum  itself  as  it  revolves,  the  drum  being  introduced  into  the 
primary  circuit.     Two  binding  screws  are  placed  on  the  stand,  but 


202 


PRACTICAL  PHYSIOLOGY. 


[xxxv. 


one  is  insulated.  The  axis  of  the  drum  carries  a  horizontal  (adjust- 
able) arm  or  "  striker  "  carrying  a  platinum  wire  which  touches  a 
wire  fixed  on  a  support  on  the  insulated  binding  screw.  Thus  every 
time  the  drum  revolves  a  shock  is  induced,  and  always  at  the  sajue 
moment,  so  that  successive  shocks  can  be  recorded  on  the  same 
abscissa  and  the  moment  of  stimulation  can  be  found  at  once. 

3.  Simple  Muscle-Curve  with  Crank-Myogi*aph  and  Automatic 
Break. — Apparatus  required. — (1)  Recording- drum  moving  at  a 
fast  rate  (about  50  cm.  per  second);  (2)  crank-myograph ;  (3) 
chronograph  vibrating  100  times  per  second  ;  coil ;  keys. 


F16.  120.— Arrangement  for  analysis  of  Muscle-Curve  by  means  of  Crank-Myograph  (JO 
with  "  Automatic  Break  "  Arrangement  in  Primary  Circuit.  S.  Striker  on  axis  of  D 
cylinder;  P.C.  Primary,  and  S.C.  Secondary  circuits;  T.C.  TimL-ciicuit  witli  E.M. 
Electro-magnet ;  I.S.  liisulated  support  in  P.C. 

(a.)  Arrange  the  apparatus  as  in  fig.  120.  The  cylinder  (D)  is 
placed  in  the  primary  circuit.  Wlien  the  horizontal  arm  or  striker 
(S)  fixed  to  the  vertical  spindle  touches  the  upright,  the  primary 
circuit  is  made  and  broken  and  induction  shocks  are  induced  in  the 
secondary  circuit.  Select  a  break  shock,  i.e.,  when  the  make  is  not 
yet  effective.  The  vertical  support  (I.S)  is  insulated  from  the 
base  of  the  drum  support. 

(b.)  Short-circuit  the  secondary  current,  arrange  a  nerve-muscle 
preparation   on   a   crank-myograph    (M),  place   the  nerve  on   the 


XXXVI.]       ISOTONIC   AND   ISOMETRIC   CONTRACTIONS.  203 

electrodes,  arrange  the  weighted  writing-lever  to  write  on  the 
drum. 

(c)  Arrange  the  lever  of  a  chronograph  (vibrating  loo  times  per 
second  and  actuated  by  a  Grove's  cell  in  circuit  with  a  tuning-fork, 
T.C  time-circuit)  so  that  the  one  writing  point  records  exactly 
under  the  other. 

Make  base  lines  and  ordinates — muscle-lever  and  time-lever — 
on  the  cylinder  to  mark  the  relative  positions  of  the  two  writing 
points,  or  cause  one  to  write  exactly  over  the  other. 

(d.)  Adjust  the  position  of  the  break  key  in  order  to  have  the 
tracing  near  the  middle  of  the  paper  and  not  near  where  it  is 
gummed.  Open  the  short-circuiting  key,  set  '  the  chronograph 
vibrating,  and  the  cylinder  in  motion  during  one  revolution.  When 
the  striker  (S)  comes  in  contact  with  support  (I.S)  a  break 
induction  shock  is  obtained,  and  the  muscle  records  a  simple  muscle- 
curve.     Close  the  short-circuiting  key. 

(e.)  Record  the  moment  of  stimulation  by  bringing  S  into  contact 
with  the  style  on  I.S.  The  distance  between  this  point  and  the 
beginning  of  the  curve  indicates  the  latent  period. 

(/.)  Study  the  "muscle-curve"  (fig.  121),  noting  particularly 
the  latent  period,  the  ascent  and  descent.  The  latent  period  may 
be  represented  by  a  distance  of  4  or  5  millimetres,  but  this  delay 
does  not  represent  the  actual  latent  period,  which  is  really  much 
shorter.  The  long  latent  period  is  really  largely  due  to  the 
apparatus  and  therefore  instrumental.  Estimate,  by  means  of  the 
tuning-fork  vibrations,  the  duration  of  each  of  the  phases. 


LESSON  XXXVI. 


ISOTONIC  AND  ISOMETRIC  CONTRACTIONS- 
WORK  DONE— HEAT-RIGOR. 

1.  Isometric  v.  Isotonic  Contraction  (Fick). — In  the  ordinary 
way  of  recording  a  simple  muscular  response  or  twitch,  as  just 
described,  a  hglit  lever  (with  a  Hght  weight  attached)  records  its 
movements,  so  that  the  muscle  is  constantly  stretched  by  and  con- 
tracts against  a  small  constant  resistance  during  its  contraction. 
Such  a  curve  is  isotonic  (fig.  121). 

If,  however,  the  muscle  contracts  by  pulling  on  a  strong  spring  of 
great  resistance, — such  a  spring,  for  example,  as  requires  about  500 
grams  to  bend  it  slightly, — then  the  curve  obtained  is  isometric. 
The  curves  obtained  by  clinical  dynamometers  are  of  this  class. 


204 


PRACTICAL   PHYSIOLOOY. 


[XXXVI 


For  isometric  curves  Fick  attached  a  muscle  to  the  short  arm  of  a  lever,  the 
other  arm  being  prevented  from  moving  much  by  the  resistance  of  a  strong 
spring.  In  this  way  one  obtains  a  curve,  which  shows  little  change  of  form, 
but  indicates  the  increase  and  decrease  of  tension  during  the  contraction,  the 
length  of  the  muscle  remaining  nearly  constant,  and  for  this  reason  Fick 
called  it  "  isometric."  <^»  fonrsfl  an  absolutely 
recorded. 


Ot  course  an  absolutely  isometric  curve  cannot  be 


FiQ.  xai.— ^luscle-Curve  of  Frog^s  GastrocnemiuB.    The  lower  line  indicates  time, 
and  each  double  vibration  (D.  V.)=^}^j^  sec 


If  one  compares  an  isotonic  and  isometric  curve  from  the  same  muscle,  one 
finds  that  the  apex  of  the  isometric  curve  lies  nearer  the  beginning  of  the 
contraction  than  mat  of  the  isotonic  curve,  i.e.,  the  length  remaining  the 
same,  the  isometric  curve  reaches  the  maximum  of  its  tension  sooner  than  it, 

the  tension  being  the  same, 
reaches  the  maximum  of  its 
shortening.  Moreover,  the  iso- 
metric curve  is  flat-topped,  so 
that  it  remains  for  some  time  in 
contraction  (fig.  122). 


2.  Registration  of  Ten- 
sion of  a  Muscle  (Fick). — 
When  the  two  ends  of  a 
muscle  are  so  fixed  that 
during  activity  they  cannot 
approximate  towards  each 
other,  then  the  muscle  does 

not   change  its   length  but  only  its   tension.     Fick  calls   this   an 

"  isometric  "  method. 

One  can  record  the  change  in  tension  by  means  of  a  "  tension- 


Fia.  Z22.— a.  Diagram  of  isotonic,  &,  isometric 
muscle-curves. 


XXXVI.]       ISOTONIC    AND    ISOMETRIC    CONTRACTIONS.  20$ 

recorder"  devised  by  Fick  (fig.  123).  One  end  of  the  muscle  is 
fixed,  the  other  is  attached  Idj  means  of  an  inextensible  thread 
which  passes  round  a  small  pulley  fixed  on  a  steel  axis  (A).  This 
axis  carries  (i)  a  long  light  recording  lever  (Z),  and  (2)  a  hori- 
zontally placed  steel  spring  (F)  whose  free  end  rests  on  a  support 
(w).  When  the  muscle  contracts,  the  spring  (F)  is  pressed  against 
the  support  (u).  In  consequence  of  the  opposing  tension  of  the 
spring  the  axis  can  only  be  turned  slightly,  but  this  movement  is 
greatly  amplified  by  the  recording  lever. 

Schonlein  has  devised  a  myograph  (Pfliiger's  ArcTiiVy  Bd.  52,  p. 
112),  which  is  so  arranged  that  one  can  record  either  isotonic  con- 
tractions or  isometric  contractions.  The  isometric  curves  so 
obtained  have  been  called  "  tonograms."  The  apparatus  is  made 
by  W.  Siedentopf  in  Wiirzburg. 

3.  Work  Done  duiing  a  Single  Contraction. — Arrange  a  gastroc- 
nemius to  record  on  a  cylinder,  but  record  only  the  "  lift,"  as  in 


Z  ^       ^ 


T? 


FiO.  123.— Scheme  of  Fick's  Tension-recorder.    A.  Axis  movement ;  F.  Strong  spring 
resting  on  support  u ;  Z.  Writing-lever. 

Lesson  XXXIV.,  the  cylinder  being  stationary,  moving  the 
cylinder  with  the  hand  as  required.  On  the  lever  under  the 
muscle  attachment  place  a  scale-pan,  and  in  this  place  weights  of 
known  value.  With  each  twitch  the  muscle  lifts  the  weight,  and 
thus  does  a  certain  amount  of  work  which  is  easily  calculated 

{a)  Measure  the  height  of  the  tracing  from  the  base  line  or 
abscissa.  This  is  conveniently  done  by  a  paper  millimetre  scale 
fixed  to  a  microscopic  slide.  The  work  done  (W)  is  equal  to  the 
weight  {w)  lifted  multipHed  by  the  height  (//)  to  which  it  is  lifted — 

W  =  m;A. 

But,  of  coui-se,  a  long  lever  being  used,  the  tracing  is  much  higher 
than  the  actual  shortening  of  the  muscle. 

{h.)  To  determine  the  exact  amount  of  the  lift,  one  must  know  the 
length  of  the  lever  and  the  ratio  between  its  arms.  Suppose  the 
one  to  be  ten  times  as  long  as  the  other,  then  the  total  work  in 
gram-millimetres  must  be  divided  by  10. 


2o6 


PRACTICAL  PHYSIOLOGY. 


[XXXVII. 


(• .)  To  determine  the  greatest  amount  of  work  obtainable, 
\;irioiis  heights  must  be  tried  to  get  the  largest  product,  care 
being  taken  not  to  fatigue  the  muscle. 

4.  Curve  of  Heat-Rigor.  —  (a. ) 
Arrange  a  frog's  gastrocnemius  to 
record  by  means  of  a  crank -myo- 
graph on  a  slow-revolving  drum, 
weighting  it  with  30-50  grams. 
Inscribe  the  continuous  change  of 
form  of  the  muscle  produced  by 
pouring  water  at  70°  C.  on  the 
muscle. 

(6.)  Or,  use  the  following  appa- 
ratus devised  by  Ludwig,  where, 
however,  the  sartorius  is  used  in 
place  of  the  gastrocnemius,  as  it 
has  parallel  fibres  (fig.  124). 

6.     Chordogram.  —  Engelmann 
(Croonian  Lecture,  R.  S.  1895)  has 
shown  that,    when  a  short  length 
(5  cm.)  of  an  E  violin  string,  pre- 
viously swollen  in  water,  is  fixed 
80  as  to  record  any  alteration  in 
its  length,  on  suddenly  heating  the 
string  the  lever  rises,  and  on  cool- 
ing the  lever  falls  and  a  curve  is 
recorded  just    like    a    contraction 
curve  of  muscle.     Or  a  string  may  be  made  to  swell  by  dipping  in  hot  water 
and  then  soaking  in  concentrated  glycerin.     This  can  then  be  heated  in  air 
and  the  movements  recorded. 


FlQ.   124 


-Apparatus  for  obtaining  the  curve 
of  a  sartorius  in  heat-rigor. 


LESSON  xxxvn. 


PBNDULUM-MYOGRAPH- 
DESPRBTZ 


-SPRING-MYOGRAPH- 
SIGNAL. 


1    Pendulum-Myograph  Muscle-Curve. 

(a.)  Cover  the  oblong  glass  plate  with  glazed  paper,  smoke  its 
tiurfaee,  and  fix  it  to  the  pendulum.  The  plate  must  be  so  adjusted 
that  the  pendulum,  on  being  set  free  from  the  "detent"  (fig.  125, 
C),  shall  be  held  by  the  "  catch  "  (C).     Test  this. 

{b.)  Arrange  the  primary  circuit  for  single  shocks  as  in  fig.  125, 
interposing  the  trigger-key  or  knock-over  key  of  the  pendulum- 
myograph  (K').     Short-circuit  the  secondary  coil. 

(c.)  Fix  the  femur  of  a  nerve-muscle  preparation  in  the  clamp, 
attach  the  tendo  Achillis  to  the  writing-lever  (S),  and  place  the 


XXXVII.] 


PENDULUM-MYOGRAPH. 


207 


nerve  over  the  electrodes  in  a  moist  chamber  or  use  a  crank-myo- 
graph.  Load  tlie  lever  with  20  grams,  and  direct  its  point  to  the 
side  to  wliich  the  pendulum  swings.  Yix  the  pendulum  with  the 
detent,  and  adjust  the  writing-style  of  the  lever  on  the  smoked 
surface.  Connect  the  electrodes  (or  wires)  from  muscle  or  nerve  to 
the  short  circuiting  key 
in  the  secondary  circuit 
(omitted  in  fig.    125). 

After  opening  the 
secondary  circuit,  with  the 
hand  break  the  primary 
circnit  to  make  certain 
that  the  muscle  responds 
at  break. 

(d.)  Close  the  trigger- 
key  (K')  in  the  primary 
circuit,  and  open  the  key 
in  the  secondary  circuit. 
Allow  the  pendulum  to 
swing ;  as  it  does  so,  it 
knocks  over  the  key  in 
the  primary  circuit  and 
breaks  the  current,  thus 
inducing  a  shock  in  the 
secondary  circuit,  whereby 
the  muscle isstimulated  and 
caused  to  record  its  con- 
traction or  muscle-curve 
on  the  smoked  surface. 

(e.)  Abscissa,  i.e.,  the  base  line, 
the   muscle   to   remove  the  writing 
recordinej  surface. 


FlO.  125.— Scheme  of  the  Arrangement  of  the  Pen- 
dulum. B.  Battery ;  /.  Primary,  //.  Secondary 
spiral  of  the  induction  raacliine ;  S.  T<ioth  ;  A''. 
Key ;  C,  C.  Catches  ;  K'  in  the  corner,  Scheme  of 
K' ;  K.  Key  in  primary  circuit.  It  is  well  to  have 
a  short-circuiting  key  in  the  secondary  circuit. 


Rotate  the  stand  supporting 
point  of  the  lever  from  the 
Bring  th(7  pendulum  back  to  the  detent,  adjust 
the  writing-style,  close  the  trigger-key,  and  keep  the  secondary  cir- 
cuit short-circuited.  Allow  the  pendulum  to  swing.  This  records 
the  base  line. 

(/)  Latent  period. — Bring  the  pendulum  to  the  detent,  short- 
circuit  the  secondary  circuit,  and  withdraw  the  writing-style  as  in 
(e.).  Close  the  trigger-key,  with  a  finger  of  the  left  hand  keep  it 
closed,  allow  the  lever  to  touch  the  glass  plate  in  its  original  posi- 
tion, and  with  the  right  hand  bring  the  knife-edge  of  the  pendulum 
in  contact  with  the  trigger-key,  so  as  just  to  open  it.  A  curved 
line  is  inscribed  on  the  stationary  plate,  which  indicates  the  moment 
of  stimulation. 

{g.)  Time-Curve. — Remove  the  muscle-lever,  place  the  pendulum 
in  the  detent,  close  the  trigger-key,  take  a  tuning-fork,  vibrating. 


208 


PRACTICAL  PHYSIOLOGY. 


[XXXVIl. 


say,  1 20  or  250  double  vibrations  per  second,  and  adjust  it-s 
writing-style  in  the  position  formerly  occupied  by  the  style  of  the 
muscle-lever.  Set  the  fork  vibrating,  either  electrically  or  by 
striking  it.     Allow  the  pendulum  to  swing,  when   the   vibrating 


i 


f 


r 


250  DV.  I 

FiQ.  126. — Pendulum-Myograph  Curve.    S.  Point  of  stimulation ;  A.  Latent  period ; 
B.  Period  of  shortening,  and  C.  of  relaxation. 

tuning-fork  vnll  record  the  time-curve  under  the  muscle-curve  (fig. 
126,  250  DV).  All  the  conditions  must  be  exactly  the  same  as 
when  the  muscle-curve  was  taken. 


FlO.  127.— Spring-Myograph. 

(7l)  Varnish  the  curve,  and  measure  its  phases.  Bring  ordinates 
vertical,  a',  h\  c',  to  the  abscissa,  and  measure  the  "latent  period  " 
(fig.  126,  A),  the  duration  of  the  shortening  (B),  the  phase  of 
relaxation  (C),  and  the  contraction  remainder. 

2.  Spring-Myograph  (fig.   127). — The  arrangements  are  exactly 


XXXVII.] 


PENDULUM-MYOGRAPH. 


209 


fix  it  in 


tlie  same   as  for  the  pendulnm-myograph,  the  trigger-key  of  the 
myograph  being  placed  in  the  primary  circuit. 

(a.)  Cover  the  glass  with  glazed  paper,  smoke 
the  frame.     Push  the  plate  to 
one  side,  and  fix   it  with  the 
catch.      Close   the   trigger  key 

(b.)  ^fake  a  nerve-muscle 
preparation,  and  arrange  it  to 
write  on  the  glass  plate.  Open 
the  secondary  circuit. 

(c.)  Press  on  the  thumb- 
plate  (a),  thus  liberating  the 
spring,  when  the  glass  plate 
shoots  to  the  other  side,  when 
the  tooth  {(I)  on  its  under 
surface  breaks  the  primary 
circuit,  and  the  muscle-curve 
is  recorded. 

(d.)  Short-circuit  the  second- 
ary circuit,  push  back  the 
plate,  and  fix  it  with  the 
catch;  close  the  trigger-key, 
and  shoot  the  plate  again  to 
record  the  abscissa. 

(e.)  Make  a  time-curve.     Push  the  plate  back  again 
close  the  trigger-key — in  order 


FlO.  128.— Arrangement  for  Estimating  the 
Time-Relations  of  a  Single  Muscular  Con- 
traction. B.  Battery  ;  K.  Key  in  primary 
circuit;  /.  Primary,  //.  Secondary  coil, 
without  a  short-circuiting  key  ;  I.  Muscle- 
lever;  e.  Electro-magnet  in  primary  cir- 
cuit ;  t.  Electric  signal ;  St.  Support ;  RC. 
Revolving  cylinder.  Introduce  a  short- 
circuiting  key  into  the  secondary  circuit. 

and  fix  it ; 
that  the  conditions  may  be  exactly 
the  same  as  before — set  a  tuning-fork  in  vibration  (120  double 
vibrations  per  second),  and  adjust  its  writing-style  under  the 
abscissa.     Shoot  the  plate  again,  and  record  the  time-curve. 


ADDITIONAL  P:XERCISES. 


3.  Study  the  improved  form  of  this  instrument  recently  introduced  hy  Du 
Bois-Reymond  in  which  the  glass  plate  is  set  free,  and  the  tuning-fork  vibra- 
tions are  recorded  sinuiltaneously  when  a  handle  is  pressed.  It  has  a  simple 
mechanism  for  adjusting  the  writing-styles  for  the  muscle  and  abscissa. 

4.  Analysis  of  Twitch  on  a  Revolving  Drum. 

{a.)  Arrange  the  drum  to  move  at  a  fast  speed  (50  cm.  per  sec). 

(&.)  Arrange  an  induction  coil  for  single  B,  shocks,  the  secondary  circuit 
short-circuited,  and  arranged  to  stimulate  a  nerve  attached  to  a  muscle  placed 
in  a  moist  chamber,  or  on  a  crank-myograph,  as  directed  for  the  foregoing 
experiments.  In  the  primary  circuit  introduce,  besides  the  spring-key,  an 
electro-magnet  with  a  marking  lever  (figs.  116,  128,  e),  and  cause  its  point  to 


210 


PRACTICAL  PHYSIOLOOY. 


[XXXVII. 


write  exactly  under  the  muscle-lever.  Arrange,  with  its  point  exactly  under 
the  other  two,  a  Despretz  chronograph  or  signal,  in  circuit  with  a  tuning-fork 
o!  known  rate  of  vibration,  and  driven  by  means  of  a  Grove's  cell  (fig.  129). 
Tlie  three  recording  levers  are  all  fixed  ou   the  same  stand,  which  should 


Fig.  129. — Signal  and  Vibrating  Tuning-Fork  in  an  Electric  Circuit.    D.  Drum  ; 
C.  Signal ;  EM.  Electric  tuning-fork  ;  Pt.  Platinum  contact. 

preferably  be  a  tangent  one,  i.e.,  the  rod  bearing  the  recording  styles  can  by 
means  of  a  handle  be  made  to  rotate  so  as  to  bring  the  writing-styles  in  con- 
tact with  the  recording  surface. 

On  opening  the  secondary  circuit  and  breaking  the  primary  one,  the  muscle 
contracts,  and  at  the  same  time  the  style  of  the  electro -magnet  is  attracted 
and  records  the  exact  moment  of  stimulation  (fig.  116). 

5.  Despretz  Signal  (figs.  129,  130). — This  small  electro-magnet  has  so  little 
inertia  that,  if  it  be  introduced  into  an  electric  circuit,  its  armature,  which 


FlO.  130.— ..espretz  Electric  Signal  or  Chronograph,  as  made  by  the  Cambridge 
Scientific  Instrument  Company. 

is  provided  with  a  very  light  writing  point,  vibrates  simultaneously  with 
the  vibrations  of  an  electric  tuning-fork  introduced  into  the  same  circuit. 
Arrange  the  signal  and  tuning-fork  as  in  fig.  129.  The  drum  must  move 
more  rapidly,  the  more  rapid  the  vibrations  of  the  tuning- fork  used.     Use  a 


XXXVII.] 


PENDULUM-MYOGRAPH. 


211 


Grove's  cell.     The  analysis  may  also  be  done  by  means  of  the  "  automatic 
break  "  arrangement  attached  to  the  revolving  drum  (Lesson  XXXV.). 


FiQ.  131.- Chronograph  arranged  to  Write  on  a  Horizontal  Cylinder,  as  made  by  Veidln. 


Fig.  132.— Marey'8  Simple  Myograph,  as  made  by  Verdin, 
6.  Vibrating  Reed  as  a  Chronograph. — For  measuring  small  intervals  of 
time  this  is  very  convenient.     The  arrangement  was  first  adopted  by  Grun- 


212 


PRACTICAL  PHYSIOLOGY. 


[xxxvii. 


mach,  acting  on  the  suggestion  of  Kronecker.  A  steel  tongue,  vibrating  a 
hundred  times  per  second,  covers  an  oblong  aperture  placed  at  the  lower  part 
of  a  gradually-narrowing  brass  tube,  closed  at  the  narrow  end.  To  the 
tongue  is  attached  a  stylette,  which  records  the  movements  of  the  former.     To 


si 


"^1 

a  •' 
a  o 

1- 

11 
i§ 

3o 
si«5 


»?**• 

f 


the  open  end  of  the  brass  tube  of  the  instrument  is  attached  a  brass  ball  or 
resonator,  and  to  the  latter  a  caoutchouc  tube.  When  air  is  sucked  through 
the  apparatus,  the  reed  (and  with  it  the  stylette)  is  set  vibrating.  It  may  be 
kept  vibrating  by  means  of  an  aspirator  placed  in  connection  with  a  water- 
tap. 


XXXVIII.]  INFLUENCE  OF  TEMPERATURE,  ETC.  2/3 

7.  Marey's  Myograph  (fig.  132).-  The  pithed  frog  is  pinned  on  a  cork  plate, 
the  tendon  of  the  gastrocnemius  is  dissected  out  and  attached  to  a  writing' 
lever,  which  is  weighted  with  a  counterpoise  ;  the  sciatic  nerve  is  dissected 
out  and  stimulated  in  the  ordinary  way.  The  cylinder  moves  on  a  liorizontal 
axis.  The  muscle  can  be  stimulated  while  it  is  still  in  silu,  and  is  under 
more  normal  conditions  than  in  the  case  of  an  excised  muscle.  It  is  useful 
for  the  study  of  the  action  of  poisons  on  muscle, 

8,  Spring-Myograph  of  Fredericq  (fig.  133).— This  is  arranged  in  the  same 
way  as  the  spring-myograph,  but  the  glass  i>late  is  placed  horizontally.  The 
glass  plate  is  pulled  along  rapidly  by  a  band  of  caoutthoi^c.  A  key  in  the 
primary  circuit  is  opened  by  means  of  a  pin  attached  to  the  frame  carrvino- 
the  glass  plate  when  the  plate  is  discharged.  In  an  improved  form  of  the 
instrument,  a  steel  rod  made  to  vibrate  at  the  moment  the  plate  is  discharged 
records  a  time-curve  beside  the  muscle-curve. 


LESSON  XXXVIIL 


INFLUENCE   OP   TEMPERATURE,    LOAD,  AND 
VBRATRIA  ON  MUSCULAR  CONTRACTION. 

1.  Influence  of  Temperature  on  Muscular  Contraction. 

(a.)  Arrange  the  nerve-miiscle  preparation  on  a  crank-myograph 
— after-loaded  —  as  in  Lesson  XXXV.,  using  the  automatic  key  by 
means  of  the  drum.  All  the  curves  are  thus  taken  on  the  same 
abscissa.  Take  a  tracing  at  the  normal  temperature  of  the  room. 
Mark  the  moment  of  stimulation. 


Fig.  134.— Showing  how  the  form  of  a  Muscle-Curve  varies  with  the  temperature  of  the 
water  Howing  through  the  box,  shown  in  fig.  119.  i  at  5"  C.  ;  2  at  10*;  ^  at  15"  i 
4  at  20° ;  5  at  25° ;  6  at  ^0° ;  7  at  35* ;  and  8  at  40°  C.  The  lowest  tracing  indicates 
time,  100  D.V.  per  second,  x  the  moment  of  stimulation,  by  automatic  break. 

^  (h.)  Place  ice  upon  the  skin  over  the  gastrocnemius  far  some 
time,  or  pour  iced  salt  solution  on  the  exposed  gastrocnemius,  and 
then  take  another  tracing  on  the  same  abscissa,  noting  the  differences 


2i4  PRACTICAL  PHYSIOLOGY.  [XXXVIII. 

in  the  result.     The  contraction  is  both  much  longer  and  lower,  and 
tlie  latent  period  is  also  longer. 

('•.)  Pour  on  to  the  muscle  warm  salt  solution  and  take  another 
tracing.  Observe  the  result.  Do  not  overheat  the  muscle  or  heat- 
rigor  results  (fig.  134). 

Other  Methods, — {d.)  Adjust  a  piece  of  wire  gauze  over  the  leg,  and  allow 
it  to  project  beyond  the  end  of  the  plate  ot  the  myogra})h.  Heat  the  gau?* 
with  a  spirit-lamp.  Take  a  tracing.  The  contraction  is  shorter  than  in  1 
{h. ).     Do  not  overheat  the  muscle. 

(g.)  A  piece  of  lead-piping  of  narrow  diameter  (J  inch)  can  be  bsnt  into  the 
form  of  a  cylinder,  and  the  muscle  placed  within  it.  Water  of  various 
temperatures  can  then  be  passed  through  it. 

(/. )  The  muscle  may  be  attached  to  an  ordinary  horizontal  writing-lever. 
Surround  the  muscle  with  a  double-walled  box,  with  an  inflow  and  outflow 
tube,  through  which  water  at  diff'erent  temperatures  can  be  passed.  A 
delicate  thermometer  is  placed  in  the  chamber  with  the  muscle. 

(g.)  A  convenient  method  is  to  allow  the  muscle  to  rest  on  a  small  circular 
brass  box,  fitted  into  the  wooden  plate  of  the  crank-myograph.  The  box  (B, 
B)  is  provided  with  an  inflow  and  an  outflow  tube,  through  which  water  of 
the  desired  temperatuie  can  be  passed. 


S^Q^^C^^'^^^^'^^^ 


250  OV. 

Fig.  135.— Pendulum-ilyograph  Curves,  showing  the  Influence  of  the  Load  on 
the  Form  of  the  Curve. 

2.  Influence  of  Load  on  Form  of  Muscle-Curve. 

(a.)  Arrange  an  experiment  with  the  pendulum-myograph  as  in 
Lesson  XXXVII.,  using  either  a  muscle-lever  or  a  crank-myograph. 
Or,  arrange  a  crank-myograph  (after-loaded)  to  write  on  a  cylinder, 
the  cylinder  being  arranged  to  break  automatically  the  primary 
circuit  as  at  p.  202.     Take  all  the  curves  on  the  same  base  line. 

(b.)  Take  a  tracing  with  the  muscle  weighted  with  the  level 
only. 

(c.)  Then  load  the  lever  successively  with  different  weights  (5,  20, 
50,  70  ...  100  grams),  and  in  each  case  record  a  curve  and  observe 
how  the  form  of  the  curve  varies  (fig.  135). 

('/.)  In  each  case  record  the  abscissa  and  time-curve. 

3.  Influence  of  Veratria  on  Contraction. 

(a.)  Destroy  the  brain  of  a  frog,  and  inject  into  the  ventral 
lymph-sac  a  few  drops  of  a  i  p.c.  solution  of  sulphate  of  veratria. 


XXXVIII.]         INFLUENCE   OF  TEMPERATURE,  ETC. 


215 


When  tlie  frog  is  under  the  influence  of  the  drug,  discharge  a 
reflex  act  by  mechanically  stimulating  the  skin  of  the  leg.  The 
limbs  are  extended,  and  remain  so  for  several  seconds,  due  to  the 
prolonged  contraction  of  the  extensors  overcoming  the  flexors 
and  thus  causing  extension  of  the  legs. 

(h.)  Arrange  the  induction  machine  for  single  shocks  to  make 
and  break  the  primary  circuit  by  the  hand  by  means  of  a  contact- 


FiO.  136.— Muscle-Curve  from  a  "  Veratrised"  Muscle,  recorded  on  a  Slow-moving 
Drum.    A.  Abscissa  ;  T.  Time  in  seconds. 


key.  Short-circuit  the  secondary.  Do  not  stimulate  the  muscle 
often,  as  the  veratria  efl'ect  diminishes  with  activity  of  the  muscle. 

(c.)  Make  a  nerve-muscle  preparation  and  fix  it  on  a  crank- 
myograph.  On  dividing  the  spinal  cord  notice  the  prolonged 
extension  of  the  legs. 

Arrange  the  muscle-lever  to  record  its  movements  on  a  slow- 
revolving  drum  (1-2  cm.  per  second).  Take  a  tracing.  Note  that 
the  muscle  contracts  quickly  enough,  but  the  contraction  is  very 
high  compared  with   that  of  a   non-poisoned  muscle,   while  the 


Fio.  137.— Veratria  Curve  (Upper).    Normal  Muscle-Curve  (Lower).    Quick-moving  drum. 


muscle  relaxes  very  slowly  indeed.  The  relaxation  phase  may 
last  several  seconds,  i.e.,  a  kind  of  "contracture."  Record  half- 
seconds  or  seconds  under  the  tracing.  The  tracing  may  show  an 
uneven  curve,  due  to  irregular  spasms  of  the  muscular  fibres,  or  an 
initial  contraction  as  in  fig.  136. 

{d.)  Take  a  tracing  with  a  quick-moving  drum,  and  such  a  curve 


2l6  PRACTICAL  PHYSTOLOOY.  [XXXTX. 

as  fig.  137  will  be  obtained,  where  the  drum  goes  round  several 
times  before  the  relaxation  is  complete. 

(p.)  Note  that,  if  the  "  veratrised "  muscle  be  made  to  contract 
several  times,  the  effect  passes  off— only  a  simple  twitch  being 
obtained — but  is  re-established  after  rest.  A  high  temperature 
also  causes  it  to  disappear. 

(/.)  The  direct  action  of  veratria  on  muscular  tissue  may  also  be 
studied  by  the  apparatus  described  in  Lesson  XLIII.,  and  by  this 
method  it  is  easy  to  compare  the  form  of  the  curve  before  and 
after  the  action  of  the  poison  (fig.  137).  The  drum  makes  many 
revolutions  before  the  lever  comes  to  the  abscissa  again. 

{(J.)  Investigate  the  effect  of  heat  and  cold  in  modifying  the 
curves  obtained.     Under  heat  the  veratria  influence  passes  off. 


LESSON  XXXTX. 


ELASTICITY  AND   EXTENSIBILITY  OP   MUSCLE— 
BLIX'S  MYOGRAPH. 

1.  Extensibility  and  Elasticity  of  Muscle. 

(a.)  Dissect  out  the  gastrocnemius  of  a  frog  with  the  femur 
attached,  fix  the  femur  in  a  strong  clamp,  attach  the  tendon  to  a 
muscle-lever  with  a  scale-pan  attached.  Neglect  the  weight  of  the 
pan,  and  see  that  the  lever  writes  horizontally  on  a  drum.  It  is 
better  to  do  the  experiment  with  the  sartorius  (or  with  the  semi- 
membranosus and  gracilis,  Lesson  XXIX.),  as  they  have  parallel 
fibres. 

(h.)  Place  in  the  scale-pan,  successively,  different  weights  (10, 
20,  30,  40  .  .  .  100  grams).  On  adding  10  grams,  the  lever 
descends;  remove  the  weight  and  the  lever  ascends.  Move 
the  drum  a  certain  distance  (about  3°),  and  add  20  grams  to  the 
scale-pan.  This  time  the  vertical  line  drawn  is  longer,  indicating 
greater  extension  of  a  muscle  by  a  greater  weight,  but  nevertheless 
the  muscle  lever  will  rise  to  its  original  height  on  removing  the 
weight.  Repeat  this  with  other  weights.  With  the  heavier 
Aveights  see  that  everything  is  securely  clamped.  If  the  apices  of 
all  the  lines  obtained  be  joined,  they  form  a  hyperhola.  The 
muscle,  therefore,  has  not  a  large  amount  of  elasticity,  i.e.,  it  is 
easily  extended  by  Hght  weights,  and  on  removal  of  the  weight  it 
regains  its  original  length,  so  that  its  elasticity  is  said  to  be  perfect. 
The  hyperhola  obtained  shows  further  that  the  increase  in  length 


XXXIX.]   ELASTICITY   AND   EXTENSIBILITY  OF  MUSCLE.  217 

is  not  directly  proportional  to  the  weight,  but  diminishes  as  the 

weights  increase  (fig.  138). 

{r.)  Repeat  the  same  experiment  with  a  strip  of  india-rubber. 

In  this  case  equal  increments  of  weight  give  an  equal  elongation, 
so  that  a  line  joining  the  apices 
of     the    vertical     lines     drawn 
after  each  weight   is  a  straight 
line  (fig.  139). 


2.  The  Extensibility  of 
Muscle  is  Increased  during 
Contraction,   its   Elasticity  is 

no.  138.  —  Curve  oi  Diminished.  fio  139. -curve  of 

Eia«ioit,o,aFro».       (^ )  ^-^  j,^^  gastrocnemius-     SS""""'"- 
or  preferably  semi-membranosus 
and  gracilis — in  a  strong  clamp,  connecting  it  to  a  lever  to  record 
on  a  drum,  and  adjust  an   interrupted  current  to   stimulate  the 
muscle,  either  directly  or  indirectly. 

{h.)  Load  the  lever  with  50  grams,  and  in  doing  so  allow  the 
drum  to  move  slowly.  Remove  the  load  and  observe  the  curve 
obtained. 

(c.)  Tefcanise  the  muscle,  and,  while  it  is  contracted  to  its  greatest 
extent,  again  load  the  lever  with  50  grams  while  the  drum  is  in 
motion,  and  remove  the  load.     Observe  the  curve. 

{(1.)  Compare  the  two  curves.  The  second  curve  will,  of  course, 
begin  higher,  but  notice  that  its  absolute  descent  is  greater  than 
the  first  curve,  and  that  it  does  not  rise  to  the  horizontal  again. 

(e.)  It  is  better  to  begin  the  experiment  with  the  drum  stationary, 
and  then  to  record  the  tracing  with  the  drum  in  motion,  or  it  may 
be  done  with  a  stationary  drum. 

3.  Blix's  Myograph. — Although  this  myograph  was  described 
many  years  ago,  it  seems  to  be  but  little  used  in  this  country. 
Personally,  I  am  indebted  to  Prof.  Fick  of  Wiirzburg  for  his 
kindness  in  showing  it  to  me.  By  means  of  it  one  can  readily 
record  the  curve  of  extensibility  of  a  passive  or  an  active  muscle. 
The  following  summary  is  based  on  the  description  given  by 
Schenk. 

In  the  myograph  (fig.  140)  the  muscle-clamp  and  the  part  to  which  the 
steel  lever  is  attached  form  a  rectangular  piece,  S  S,  which  glides  in  a  slot 
formed  by  the  guides,  R  R  and  R'  R'.  The  slider,  S  S,  carries  at  a  the  axis  of 
the  lever  a  b,  and  also  a  lateral  piece,  A,  placed  at  right  angles  for  the  attach- 
ment of  the  muscle,  and  one  end  of  which  is  fixed  to  the  lever  at  b.  The 
weight  is  represented  by  P,  which  by  means  of  the  collar,  r,  presses  on  the 
lever.  This  collar,  r,  moves  to  and  fro— not  from  side  to  side — between  two 
pairs  of  fixed  studs,  1 1  and  ^^  ^. 


2l8 


PRACTICAL  PHYSIOLOGY. 


[XXXIX, 


Suppose  the  slider  tx)  be  pushed  as  far  to  the  left  that  the  axis,  a,  just  lies 
opposite  to  the  collar,  r— a  poiut  which  is  adjusted  on  the  apparatus— then 
the  tension  of  the  muscle  is  nil.  On  moving  the  slider  with  the  hand  towards 
the  right,  so  that  the  weight,  P,  acts  on  points  of  the  lever  more  and  more 
removed  from  a,  then  the  tension  of  the  muscle  increases  steadily,  when  the 
writing  point,  p,  records  the  curve  of  extension,  p,  on  a  horizontally  placed 
and  stationary  wooden  board  or  glass  plate  covered  with  smoked  glazed  paper. 
In  usiilg  the  apparatus,  board,  slot,  and  slider  are  placed  horizontally,  the 
weight,  P,  is  not  applied  directly  to/,  but  to  the  latter  the  weight  is  attached 
indirectly  by  means  of  a  cord  which  passes  over  a  pulley. 

Apparatus.— Blix's  myograph,  induction  coil  arranged  for  repeated  shocks, 
the  electrodes  being  directly  connected  with  the  muscle.  The  best  prepara- 
tion to  use  is  the  double  semi-membranosus  and  gracilis  (Lesson  XXIX.  5) 
placed  side  by  side  and  firmly  attached  to  the  lever.  For  these  muscles  taken 
from  a  large  Jiuna  esculent  a  a  weight  of  2  kilos  is  used,  and  for  the  corre- 
sponding gastrocnemius  i  kilo. 


FlO  T40.— Scheme  of  Blix's  Myograph.  S,  S.  Slider ;  R  R  and  R  R.  Guides  for  slider;  a,  b. 
Lever ;  A  for  muscle  ;  P.  Weight ;  r.  CJollar ;  1 1  and  ti  tj.  Guides  for  collar  carrying 
weight ;  p.  Recording  point 

(a.)  Take  a  curve  of  a  passive  muscle  from  the  point  of  greatest  tension  to 
nil  tension. 

{b.)  Take  a  similar  curve  from  a  tetanlsed  muscle.  Compare  the  two 
curves,  and  it  will  be  found  that  the  curve  of  extensibility  of  the  passive 
mu.scle  is  less  steep  than  that  of  the  tetanised  muscle,  i.e.,  a  contracted 
muscle  is  more  extensible  than  a  passive  one. 

{>:.)  On  a  tetanised  muscle,  move  the  slider  so  that  the  tension  is  increased 
from  nil  to  the  greatest  possible,  i.e.,  the  muscle  is  more  and  more  "loaded," 
and  then  reverse  this,  so  that  from  the  greatest  tension  there  is  gradually 
"unloading."  The  two  curves  so  obtained  do  not  coincide:  the  latter  lies 
considerably  below  the  former.  It  would  therefore  a})pear,  as  far  as  the  con- 
traction is  concerned,  that  it  is  not  a  matter  of  indifiference  whether  the 
muscle  is  being  gradually  "loaded"  or  "unloaded." 

4.  Elasticity  of  an  Artery. — Test  the  elasticity  of  a  strip  of  aorta  in  the 
same  way. 


xu] 


TWO  SUCCESSIVE  SHOCKS. 


319 


LESSON  XL. 

TWO  SUCCESSIVE  SHOCKS- 
METRONOME. 


-TETANUS— 


1.  Two  Successive  Shocks.— The  primary  current  may  be 
broken  by  means  of  a  revolving  drum,  i.e.y  using  the  automatic  key 
(fig.  120).  Two  strikers  can  easily  be  arranged  on  the  same 
support  (IS),  and  their  angular  deviation  can  easily  be  adjusted  to 
give  any  required  intervaj  between  the  two  successive  shocks. 
^  Fig.  141  shows  several  tracings  indicating  the  effect  of  summa- 
tion  or  superposition  of  one  contraction  on  another,  and  how  the 
result  varies  with  the  particular  period  or  phase  of  the  contractioD 
at  which  the  second  shock  or  stimulus  is  applied. 


Fig.  141.— Effects  of  two  Successive  Shocks  011  a  Muscle,  i.  Second  stimulus  applied 
at  X  ;  2.  Second  stimulus  applied  at  the  second  x  ;  3.  Second  stimulus  applied  a^  X  S 
4.  Second  stimulus  applied  at  the  second  x. 

Make  four  successive  experiments,  using  break  shocks. 

(i.)  Arrange  the  two  closures  for  stimulation  so  that  tb^y  are  a 
full  muscle-curve  apart.  The  second  is  usually  slightly  higher  than 
the  first  (fig.  141,  1). 

(ii.)  Arrange  on  a  different  part  of  the  cylinder,  but  on  the  same 
abscissa,  so  that  the  second  stimulus  comes  in  on  the  relaxation  of 
the  foregoing  contraction.  As  the  second  contraction  occurs  before 
the  first  one  has  ended,  it  starts  from  a  higher  level  (fig.  141,  2). 

(iii.)  If  the  second  stimulus  is  so  arranged  as  to  be  thrown  in  on 
the  ascent  of  the  first  curve,  and  before  the  apex  is  reached,  the 


220 


PRACTICAL  PHYSIOLOGY. 


[XI* 


second  curve  is  superposed  on  the  first,  and  the  height  of  the  com- 
pound is  greater  than  the  original  muscle-curve  (fig.  141,  3). 

(iv.)  Apply  the  second  stimulus  within  the  latent  period  of  the 
first  contraction.  There  is  practically  no  alteration  in  the  height 
of  the  curve  (fig.  141,  3). 

2.  Tetanus. — A  tetanising  current  may  be  obtained  by  Neef's 
hammer,  or  by  means  of  a  vibrating  rod.     Apparatus. — Daniell's 


Fio.  14a.— Scheme  of  arrangement  for  Tetanus.     VS.  Vibrating  spring ;  M.  Cup  for 
mercury.    Other  letters  as  before. 

jell,  five  wires,  flat  spring,  cup  of  mercury  in  a  wooden  stand, 
induction  coil,  13u  Bois  key,  drum  moving  at  the  rate  of  5  cm. 
per  second, — i  e.,  the  cylinder  moves  once  round  in  ten  seconds, — 
crank-myograph. 

(a.)  Arrange  the  experiment  as  in  fig.  142 ;  the  induction  coil 
for  single  shocks,  short-circuiting  the  secondary  circuit.  Place  in 
the  primary  circuit  the  flat  metallic  spring,  held  in  a  clamp.  One  end 
of  the  spring  has  a  needle  fixed  at  right  angles  to  it,  wliich  dips  into 
a  cup  of  mercury.     The  needle  hangs  just  above  the  mercury  cup 


Fio.  143.— Curves  of  incomplete  and  almost  complete  Tetanoa. 


when  the  spring  is  at  rest,  but  dips  in  and  out  of  the  mercury  when 
it  vibrates.  The  clamped  end  of  the  spring  is  connected  with  the 
battery,  while  the  mercury  cup  is  connected  with  the  induction 
coil.  Cover  the  mercury  with  alcohol  and  water  (i  :  3),  to  prevent 
oxidation,  and  to  keep  the  resistance  more  uniform.  Select  a 
strength  of  shock  wliich  gives  response  only  at  break,  thus  eliminat- 
ing the  make  shocL 


XL.] 


TWO  SUCCESSIVE   SHOCKS — TETANUS. 


221 


(6.)  Arrange  a  nerve-muscle  preparation  as  in  fig.  119  to  record 
^.     on  a  slow-moving  drum.     Let  the  writing-lever  be  a  short  one. 
■  {(\)  Fix  the  flat   spring  firmly  in    the  clamp,  with    ten  inches 

K       projecting.     Allow  the  drum  to  revolve,  set  the  spring  vibrating, 
m      and  while  it  is  doing  so,  open  the  key  in  the  secondary  circuit,  and 
before  the   spring   ceases   to   vibrate   short-circuit   the   secondary 
current. 

(d.)  Shorten  the  vibrating  spring  and  repeat  the  experiment, 
making  the  tracing  follow  the  previous  one. 

(e.)  Make  several  more  tracings  on  the  same  abscissa,  and  let 
them  follow  each  other  at  regular  intervals,  always  shortening  the 
springs  until  the  tracing  no  longer  shows  any  undulations,  i.e., 
until  it  has  passed  from  the  phase  of  "  incomplete  "  to  "  complete 
tetanus." 


Fio.  144.— Tetanus  Interrupter.     W.  Wood  block ;  VS.  Vibrating  spring;  BS,  BSF.  Bind- 
ing screws  ;  C.  Movable  clamp  ;  C.  Clamp  to  fix  spring ;  M.  Cup  of  Mercury. 

(/,)  Take  a  tetanus-curve  by  introducing  Neef's  hammer  (Helm- 
holtz's  side  wire)  instead  of  the  vibrating  flat  spring. 

{(/.)  Study  the  tracings.  The  first  tracings  are  indented,  but 
gradually  there  is  more  and  more  fusion  of  the  teeth,  until  a  curve 
unbroken  by  depressions  is  obtained.  In  the  curve  of  complete 
tetanus  the  ascent  is  at  first  steep,  then  slightly  more  gradual, 
speedily  reaching  a  maximum,  when  the  lever  practically  records  a 
horizontal  line  parallel  to  the  abscissa.  When  the  current  is  shut 
off  the  descent  is  very  steep  at  first,  and  towards  the  end  very 
slow. 


3.  Number  of  shocks  required  to  produce  tetanus  depends  on  the  animal, 
the  muscle,  and  the  condition  of  the  latter  ;  the  more  fatigued  a  muscle  is,  the 
slower  it  contracts,  and,  therefore,  the  more  readily  does  fusion  of  contractions 
take  place.     A  fresh  fro  's  gastrocnemius  requires  about  27-30  shocks  per 


222 


PRACTICAL  PHYSIOLOGY. 


[XL. 


second  to  produce  complete  tetanus.     The  following  table  shows  approximately 
the  number  of  shocks  per  second  required  to  produce  tetanus. 


Shocks  per  second. 

Tortoise, 

2            {Marey), 

Frog  (hyoglossus), 

10-15 

,,    (gastrocnemius),     . 

27-30 

Lobster  (claw),  . 

20            {Richet). 

.,        (tail),    . 

40            {Richet). 

Rabbit  (red  muscle),     . 

4-10    \{KronfJcker 

j       and  Stirling). 

(white    „    ),     . 

Bird,      . 

100            {Richet). 

Insects,  . 

300-400     {Marey). 

If  the  muscle  be  fatigued,  then  more  or  less  complete  fusion  takes  place 
with  a  smaller  number  of  shocks  per  second. 

4.  Take  a  tracing  with  10  or  15  vibrations  per  second,  and  then  test  the 
effect  of  different  temperatures  on  the  form  of  the  tracing.  Pour  on  the 
muscle  normal  saline  at  the  required  temperature.  Notice  how  cold  helps 
the  fusion,  while  heat  makes  the  tetanus  less  complete. 

5.  If  Ewald's  coil  be  used  (fig.  95)  any  number  of  shocks  from  i  to  200  per 
second  can  be  obtained. 


ADDITIONAL  EXERCISES. 


6.  Interruption  by  a  Metronome. — Instead  of  the  vibrating  rod  or  Neefa 

hammer,  introduce  into  the  primary 
circuit  a  metronome  (fig.  145),  pro- 
vided with  a  wire  which  dips  into  a 
mercury  cup  introduced  into  the 
primary  circuit.  Vary  the  rate  of 
vibration  of  the  metronome,  and  ob- 
serve the  effect  on  the  muscle-curve. 

7.  Instead  of  using  the  spring  held 
in  a  clamp,  a  convenient  form  is  sliown 
in  fig.  144.  The  spring  is  kept  vibrat- 
ing by  an  electro-magnet  actuated  by 
two  Grove  cells. 

8.  Magnetic  Interrupting  Tuning- 
Fork. — Instead  of  a  vibrating  spring, 
the  primary  current  may  be  inter- 
ru})ted  by  means  of  a  tuning-fork  of 
known  rate  of  vibration,  and  kept  in 
motion  by  means  of  an  electro-magnet. 
The  instrument  (fig.  146)  is  introduced 
into  the  primary  circuit,  and  every 
time  the  style  on  one  of  the  arms  of  the 
tuning-fork  dips  into  and  comes  out 

of  the  mercury  placed  in  a  small  cup,  the  primary  current  is  made  and  broken. 


Fio.  145.— Metronome. 


XLI.]  FATIGUE   OF  MUSCLE.  223 

One  of  the  most  important  points  in  connection  with  the  use  of  tliis  instrument 
is  to  keep  the  surface  of  the  mercury  clean  and  bright.     This  is  necessary  in 


Fig.  146.— Magnetic  Interrupter  with  Tuning-Fork,  as  made  by  the  Cambridge  Sclentiflo 
Instrument  Company. 

order  to  have  the  successive  shocks  of  equal  intensity.  Kronecker  has  devised 
such  an  apparatus.  The  vibrating  rod  is  so  adjusted  that  stimuli  from  I  to 
50  or  60  per  second  can  be  obtained  therewith. 


LESSON  XLI. 
FATIGUE  OF  MUSCLE. 


1.  Fatigue  of  Excised  Muscle. 

(a.)  Arrange  an  induction  coil  for  break  shocks,  hut  interrupt 
the  primary  circuit  automatically  by  means  of  the  drum  key  (fig. 
120). 

(h.)  Fix  a  nerve-muscle  preparation  on  a  crank-myograph,  with 
a  long  lever  and  a  weight  of  40-50  grams,  lay  the  nerve  over  the 
electrodes  from  the  short-circuited  secondary  coil,  and  let  the  lever 
record  on  the  drum.  A  break  shock  is  obtained  each  time  the 
drum  revolves.  The  myograph  should  be  supported  on  a  tangent 
stand.  If  a  tangent  support  be  used  for  the  muscle-lever,  then, 
although  the  muscle  contracts  at  each  revolution  of  the  cylinder, 
one  may  record  every  tenth  or  fifteenth  contraction  just  as  one 
pleases  (fig.  147). 

(c.)  Observe  that  the  height  of  the  curves  falls,  while  their 
duration  is  longer.  In  nearly  every  case  fatigue- curves  from  muscle 
show  a  "staircase"  character  (fig.  148),  the  second  curve  being 
higher  than  the  first  one,  and  the  third  than  the  second. 

2.  Fatigue-Curve  of  Excised  Muscle. — (a.)  Use  a  slow-revolving  drum  on 
which  to  record  the  muscle  tracings,  so  slow  that  the  ascent  and  descent  of 
the  lever  form  merely  one  line.  Let  the  primary  current  be  broken  at  regular 
intervals  by  means  of  a  revolving  drum  with  a  platinum  style  attached  to  its 
spindle,  to  make  and  break  the  primary  current  at  every  revolution  (fig.  148). 
In  this  way  a  curve  such  as  fig.  148  is  obtained. 


224 


PRACTICAL  PHYSIOLOGY. 


[XLI. 


(6.)  Note  the  '*  staircase"  character  of  the  curve,  i.e.,  the  second  con  traction 
is  higher  than  the  first,  the  third  than  the  second,  and  so  on  tor  a  certain 
number  of  contractions.     After   that  the  height   of  the   contraction  falls 


Fig.  147.— Tetanns-Curve  produced  with  break  shocks  stimulation  every  second  by  means 
of  an  automatic  break  key  in  the  primary  circuit.  T.  Time-curve,  100  D.V.  per 
second. 

steadily,  so  that  a  line  uniting  the  apices  of  all  the  contractions  forms  a 
straight  line  approximately. 

In  a  fatigue-curve,  where  only  the  "lift"  is  recorded,  note  that  the  rise  of 
the  lever  increases  with  the  number  of  stimuli — the  strength  of  the  stimulus 
remaining  constant,  so  that  one  gets  the  phenomenon  of  the  "Treppe"  or 
"staircase."  After  a  time  it  falls  steadily  until  the  excitability  is  ex- 
tinguished (fig.  148).  Note  also  that  in  the  phase  of  relaxation  the  lever  does 
not  reach  the  abscissa,  i.e.,  relaxation  takes  place  so  slowly  as  if  one  had  to 


FlQ.  148. — Fatigue-Curve  of  an  Excised  Frog's  Muscle  recorded  on  a  Slow-moving  Drum. 


deal  with  a  so-called  "contracture,"  li  the  march  of  events  be  arrested,  and 
time  given  for  rej)ose,  then,  on  stimnlating,  tne  lift  increases,  but  the  effect 
lasts  only  for  a  short  time. 


xlil]  fatigue  of  nerve.  225 

LESSON  XLIL 
FATIGUE  OP  NERVE-SEAT  OP  EXHAUSTION. 

1.  Can  Nerve  be  Fatigued? — "We  have  seen  tliat  a  muscle 
manifests  fatigue,  ^.e.,  its  store  of  material  and  energy  are  gradually 
used  up,  so  tliat  it  shows  a  diminished  capacity  to  respond  to 
stimulation.  Does  a  nerve  manifest  such  phenomena?  Reasoning 
a  priori^  from  the  fact  that  the  only  known  sign  obtainable  during 
the  activity  of  a  nerve  is  the  "  negative  variation  of  the  nerve- 
current,"  one  is  led  to  suppose  that  very  probably  nerve-fibres 
partake  but  little  if  at  all  in  the  phenomena  of  fatigue.  In  fact,  we 
shall  find  that  nerve  is  practically  inexhaustible. 

Suppose  one  stimulated  a  nerve  of  a  nerve-muscle  preparation 
with  maximal  induction  shocks  until  the  muscle  ceased  to  respond 
to  indirect  stimulation.  This  would  afford  no  proof  that  the  muscle 
itself  was  fatigued.  Why  ?  Stimulate  the  muscle  directly,  and  it  will 
respond.  Therefore  the  seat  of  fatigue  in  this  case  is  not  primarily 
in  the  muscle,  but  must  be  sought  for  either  in  the  nerve  itself  or 
at  the  end-plates  where  the.  nerve  comes  into  relation  with  the 
muscular  substance. 

2.  Seat  of  Exhaustion — is  it  in  Muscle,  Nerve  or  End-Plates  ? 

A.  Not  primarily  in  Muscle. — {a.)  Arrange  an  induction  coil  for  repeated 
shocks.  Connect  the  secondary  coil  with  a  Pohl's  commutator  without  cross- 
bars. 

(6.)  Prepare  a  nerve-mascle  preparation,  with  a  straw  flag,  or  use  a  crank- 
myograph,  and  place  its  nerve  over  Du  Bois  electrodes  attached  to  the  com- 
mutator. Pass  two  fine  wires  through  the  gastrocnemius  and  attach  them  to 
the  other  two  binding  screws  of  the  commutator. 

(c.)  Tetanise  the  nerve  until  the  tetanus  ceases.  Then  reverse  the  commu- 
tator and  stimulate  the  muscle.  It  contracts.  Therefore,  ^Ae  5m<  of  fatigue 
is  not  in  the  muscle. 

B.  Not  in  the  Nerve  {Nerve  is  practically  inexhaustible). — {a.)  Arrange  a 
nerve-muscle  preparation  in  connection  with  a  coil  for  repeated  shocks  as 
before.     Place  the  nerve  over  the  electrodes  from  the  secondary  coil. 

{h. )  Arrange  a  Daniell's  cell  connected  to  N.P.  electrodes,  and  short-circuited 
for  a  constant  current— the  ' '  polarising  current "  (Lesson  XLVIII  ) — and  place 
tlie  N.P.  electrodes  next  the  muscle,  so  that  the  —  pole  is  next  the  muscle,  i.e.^ 
with  the  i)olarising  current  descending.  The  **  polarising  current"  so  lowers 
the  excitability  of  the  nerve  as  to  "block"  the  passage  of  a  nerve  impulse 
through  this  part  of  the  nerve.  The  tetanising  electrodes  are  placed  near  the 
upper  cut  end  of  the  nerve. 

(c. )  See  that  the  muscle  responds  when  the  stimulating  current  acts  on  the 
nerve,  then  throw  in  the  polarising  current,  when  at  once  the  muscle  ceases 
to  respond,  because  the  nerve  impulse  is  Islocked.  Go  on  stimulating  the 
nerve  for  an  hour  or  longer.  We  know  that  if  there  had  been  no  "  block  "  the 
muscle  would  long  ere  this  have  ceased  to  respond  to  indirect  stimulation. 

P 


226  PRACTICAL  PHYSIOLOGY.  [XLIIL 

{(i.)  Close  the  key  ot  the  i)olarising  circuit,  i.e.,  remove  the  block.  The 
muscle  responds  at  once.  Therefore  the  loss  of  excitability  or  .seat  of  cxhaus- 
tian  is  not  in  the  nerve  {Bernstein).  Where  is  it,  then  1  It  must  lie  primarily 
somewhere  between  the  nerve  and  muscle,  i.e.,  it  is  in  the  aui-filales,  or  where 
nerve  joins  muscle.  Moreover,  Bowditch  has  shown  that  the  sciatic  nerve  of 
a  curarised  cat  may  be  stimulated  for  hours,  there  being  no  muscular 
response,  but  as  soon  as  the  effect  of  curare,  which  is  known  to  paralyse  the 
nerve-terminals  in  striped  muscle,  passes  off,  the  muscles  of  the  foot  respond. 

C.  The  two  results  of  B  and  C  may  be  combined  thus  : — 

(a.)  Dissect  out  two  nerve-muscle  preparations  (A  and  B)  fi'om  a  frog, 
clamp  both  femurs  in  one  clamp,  and  attach  straw  Hags  of  different  colours 
to  both  legs  (fig.  114).  Lay  both  nerves  over  a  pair  of  Du  Bois  electrodes. 
Cover  them,  keep  them  moist. 

{b. )  Attach  the  electrode  wires  to  two  of  the  binding  screws  of  the  commu- 
tator without  cross-bars,  turning  the  handle,  so  that  the  current  can  be  passed 
through  both  nerves  when  desired. 

(c.)  To  the  nerve  of  B.  between  the  Du  Bois  electrodes  and  the  muscle, 
apply  a  "  polarising  current"  with  its  -  pole  next  the  muscle. 

{'I. )  Pass  an  interrupted  current  through  both  nerves ;  A  will  become  tetanic 
while  B  remains  quiescent :  the  impulse  cannot  pass  because  of  the  "block" 
produced  by  the  "polarising  current." 

(e.)  Continue  to  stimulate  the  nerves  until  A  ceases  to  respond.  Break 
the  polarising  current,  i.  e. ,  remove  the  block  on  B  ;  B  becomes  tetanic. 

As  both  nerves  have  been  equally  stimulated,  both  are  equally  fatigued  or 
non-fatigued.  As  B  becomes  tetanic,  the  seat  of  the  fatigue  is  not  in  the 
nerve-trunk. 

As  in  A  the  seat  of  fatigue  was  not  in  the  muscle,  and  as  B  shows  that 
nerve-fibres  practically  do  not  manifest  the  signs  of  fatigue,  it  would  seem 
that  its  seat  must  be  somewhere  between  muscle  and  nerve,  in  all  probability 
in  the  end-plates. 


LESSON  XLIII. 


MUSCLE  WAVE— MUSCLE  THICKENING— WILD'S 
APPARATUS. 

1.  This  is  best  done  by  the  method  originally  used  by  v.  Bezold, 
and  modified  in  a  simple  form  by  Biedermann.  A  muscle  with 
parallel  fibres — preferably  a  sartorius — is  fixed  a  little  to  one  side  of 
the  middle  line  in  a  cork  clamp  so  that  the  direct  transference  of 
the  change  of  muscle  form,  but  not  the  excitation  process  in  the 
muscle,  is  prevented  from  passing,  i.e.,  one  part  of  the  muscle  is 
stimulated  while  the  other  part  records. 

(a.)  Arrange  an  induction  machine  in  connection  with  a  com- 
mutator without  cross-bars  and  two  pai.s  of  thin  wires,  so  as  to  be 
able  to  send  a  single  maximum  break  shock  through  either  pair  of 
wires  as  in  the  curare  experiment  (Lesson  XXXIII.).  Let  the 
primary  current  be  broken  by  the  automatic  drum  key.     Arrange 


XLITI.]  MUSCLE  WAVE.  227 

a  recording   crank-myograph.     Arrange   time  marking    apparatus 

iiuu  )• 

(h.)  Dissect  off  with  great  care  the  sartorius  of  a  curarised  frog 
(p.  1 86),  and  connect  its  tibwl  end  with  the  myograph-lever. 

(c.)  Clamp  the  muscle  a  little  to  the  tibial  side  of  the  middle 
line  in  a  cork  clamp,  made  by  pushing  two  pins  parallel  to  each 
other  through  two  thin  pieces  of  cork  ;  the  points  of  the  pins  project 
and  serve  to  fix  the  preparation  on  the  cork  plate  of  the  myograph 

(fig.  149). 

{(1.)  Thrust  two  pins  through  the  muscle  close  to  the  clamp 
and  two  near  its  free  end.  These  act  as  electrodes  and  are  con- 
nected with  the  thin  wires  from  the  commutator,  so  that  the  muscle 
can  be  stimulated  either  near  the  clamp  or  far  away  from  it. 
Stimulate  the  muscle  first  near  the  clamp  and  record  the  contraction, 
reverse  the  commutator,  excite  it  away  from  the  clamp  and  record. 
Two  curves,  one  rising  later  than  the  other.  The  distance  between 
the  two  mdicates  the  time  taken  by  the  wave  of  contraction  to  pass 


FIQ.  149.— Arrangement  for  study  of  Muscle  Wave.    E,  E'.  Pin  electrodes ;  C.  Cork 
clamp ;  L.  Lever. 

over  the  distance  from  the  far  to  the  near  electrodes.  Measure  the 
distance  between  the  electrodes  and  calculate  its  velocity.  It  varies 
from  I  to  2  metres  per  second. 

(e.)  Test  the  effect  of  cold  normal  saline  in  slowing  its  rate. 

2,  (fi.)  Arrange  two  long  straw  levers  on  a  cork  frog-plate  so 
that  the  two  free  ends  of  the  levers  record  exactly  over  each  other 
en  a  revolving  drum.     Record  time  (j^"). 

{I).)  Remove  the  double  semi-membranosus  and  gracilis  (p.  1 79)  of 
the  thigh  from  a  curarised  frog,  together  with  their  bony  attachments, 
and  place  them  under  the  levers,  the  levers  lying  across  them,  and 
as  far  apart  as  possible.  Let  the  muscles  rest  on  paraffined  paper. 
Fix  the  muscles  through  their  bony  attachments  by  means  of  pins. 
Through  one  end  of  the  muscles  push  two  pins  attached  to  wires  to 
act  as  electrodes.  Some  prefer  the  two  sartorii  muscles,  fastened 
together,  the  one  lying  on  the  other  and  fixed  by  means  of  pins. 

(c.)  Stimulate  with  a  maximal  break  induction  sliock  and  note 
that  two  curves  on  different  abscissae  are  obtained,  the  one  a  little 


228 


PRACTICAL  PHYSIOLOGY. 


[XLIIL 


later  than  the  other.  The  distance  between  the  two  indicates  tlie 
time  taken  by  the  contraction  to  pass  from  the  one  lever  to  the 
otlier.     Test  the  effect  of  cold  normal  saline. 


Fia.  150.— Marey  3  Registering  Tambour.     Metallic  capsule,  T,  covered  with  thin  indiS' 
rubber,  and  bearing  an  aluminium  disc,  which  acts  on  the  writing-lever,  H. 

3.  Thickening  of  a  Muscle  during  Contraction. 

(a.)  Arrange  a  Marey's  tambour  to  write  on  a  pendulum-myograph  (fig. 
150). 
(6.)  Fix  Marey's  pince  mr/ographigue  (fig.  151)  so  as  to  compress  the 
adductor  muscles  between  the  thumb  and  the 
metacarpal  bone  of  the  index-finger,  keeping  the 
two  arms  together  with  an  elastic  band.  Or  use 
a  pair  of  toy  bellows,  to  the  arms  of  which  plate- 
like electrodes  are  fitted  and  connected  with  bind- 
ing screws.  Keep  the  handles  of  the  bellows 
pressed  upon  the  adductor  muscles  by  means  of 
an  elastic  band.  Connect  the  receiving  tambour 
of  the  pince  or  the  nozzle  of  the  bellows  with 
the  recording  tambour,  introducing  a  valve  or 
T-tube  with  a  screw  clamp  into  the  connecting 
elastic  tube,  to  regulate  the  pressure  of  air  within 
the  system  of  tubes. 

('•.)  Arrange  an  induction   machine   with   the 
trigger-key   of  the   pendulum-myograph   in   the 
])nniary  circuit,  and  the  pince  or  bellows  in  the 
secondary.     Take  a  tracing.     The  time  relations  of  the  contraction  are  de- 
termined in  tlie  manner  already  stated  (Lesson  XXXV IL). 


Fig.  151.— ilarey's  Pivce  Afyo- 
(jraphique,  as  made  by 
Verdi  n. 


4.  "Wild's  Apparatus  consists  of  a  glass  cylinder  made  by  inverting  the 
neck-end  of  a  two-ounce  phial.  The  neck  is  fitted  with  a  cork,  the  upper  end 
is  open  fig.  152,  B).  A  wire  connected  with  a  key  (K')  short-circuiting  the 
secondary  coil  ot  an  induction  machine  perforates  the  cork.  Arranged  above 
is  a  light  lever  (L)  provided  with  an  after-load  (a/),  and  moving  on  an  axis,  the 
short  arm  projecting  over  the  mouth  of  the  jar.  The  whole  arrangement  is 
fixed  to  a  platform  (P),  with  an  adjustable  stand  (S)  bearing  the  fulcrum  of  the 
lever  and  the  after-load.    The  cork  must  be  renewed  with  each  new  drug  used. 

(a.)  Dissect  out  the  gastrocnemius,  divide  the  femur  with  the  gastrocnemiue 


XLIV.] 


MYOGRAPHIC   EXPERIMENTS   ON   MAN. 


229 


attached  just  above  the  attachment  of  the  latter,  and  the  tibia  below  the  knee- 
joint.  Pass  a  fine  metallic  hook  tlirough  the  knee-joint  or  its  ligaments,  and 
attach  it  to  the  projecting  hoolc  of  fine  wire  fixed  to  the  short  arm  of  the  lever. 
Fix  the  tendo  Achillis  to  a  hook  connected  with  the  wire  passing  through  the 
cork  in  the  neck  of  the  glass  cylinder. 


Fio.  152:— Wild's  Apparatus  for  Studying  the  Action  of  Poisons  on  Muscle. 
P.  Platform  ;  S.  Stand  :  al.  After-load  :  L.  Lever ;  B.  Bottle  with  muscle 


D.  Drum; 
K.  Key. 


{h.)  Fill  the  glass  cylinder— which  encloses  the  muscle — not  quite  full  with 
normal  saline.  Stimulate  the  muscle  directly  with  a  break  shock,  using  a 
mercury  key  in  the  primary  circuit,  and  take  a  tracing. 

('•.)  Remove  the  normal  saline  with  a  pipette,  and  replace  it  with  a  solution 
of  the  drug  whose  action  you  wish  to  study,  e.g.,  veratria  1  in  5000,  or  barium 
chloride  i  in  1000.     Study  the  veratria  tracing  (fig.  137). 

5.  Interference -Phenomenon  in  Nerve-Muscle  Preparation. — Arrange  a 
nerve-muscle  preparation  in  a  moist  chamber,  and  weight  the  recording  lever 
with  20  grams.  Place  the  central  end  of  the  nerve  over  platinum  electrodes, 
and  allow  a  portion  of  the  nerve  nearer  the  muscle  to  hang  in  the  form  of 
a  loop  in  contact  with  strong  glycerin,  when  the  muscle  becomes  tetanic. 
When  tetanus  occurs  throw  in  an  interrupted  current,  when  the  tetanus  is 
diminished.  Is  this  interference-phenomenon  an  inhibitory  one  I  (Kaiser, 
Zeitsch.f.  Biol. J  1891,  p.  417.) 


LESSON  XLIV. 


MYOGRAPHIC  EXPERIMENTS  ON  MAN— 
ERGOGRAPH  AND  DYNAMOGRAPH. 


1.  Myographic  Experiments  on  Man. 

Fick  lias  devised  a  simple  apparatus  for  this  purpose,  using 
isometric  curves.  The  muscle  investigated  is  the  A  I/duct  or  indicts 
or  interosseus  doi\salis  primus  of  the  hand.  It  arises  by  two  heads 
from  the  adjacent  surfaces  of  the  metacarpal  bones  of  the  thumb  and 
index-finger,  and  is  inserted  into  the  dorsal  aponeurosis  of  the  latter. 


230 


PRACTICAL  PHYSIOLOGY. 


[XLIV. 


Apparatus. — In  a  prismatic  piece  of  wood,  H,  firmly  fixed  to  a  base,  a  hole 
is  cut  down  to  the  level,  K,  through  which  one  can  conveniently  place  one's 
hand  (fig.  153) ;  the  ulnar  surface  of  the  hand  rests  on  the  rounded  lower  end 

of  the  hole,  while  the  thumb  rests 
against  the  latferal  wall  of  the  hole, 
so  that  in  this  way  the  hand  is 
sufficiently  fixed.  Over  the  index- 
finger  is  placed  a  collar  made  of 
strong  iron  wire,  and  through  this 
collar  project  the  three  other 
fingers,  which  hang  free,  the  collar 
itself  lying  over  the  joint  between 
the  second  and  third  phalanges. 
To  the  collar  is  attached  a  strip  ot 
iron  with  a  notch  in  it,  by  means  of 
which  it  is  attached  to  the  axis  of 
the  lever,  which  is  one  so  arranged 
as  to  give  isometric  contractions  as 
in  fig.  153- 

When  one  attempts  to  raise  the 
index-finger,  the  muscle  records  an 
isometric  curve.  As  the  collar  can 
at  most  move  only  i  mm.,  and  as 
the  muscle  itself  acts  on  a  lever 
about  five  times  shorter  than  the 
distance  of  the  point  of  attachment 
of  the  collar  from  the  axis  of  rota- 
tion of  the  index-finger,  the  muscle 
can  at  most  contract  \  mm.  The 
muscle  records  on  a  revolving 
(From  the  description  of  Schenk.     See  Fick,  FJluger^s  Archiv,  Bd. 


Fig.  153.— Fick's  Apparatus  for  Studying  Ten- 
siun  of  Abductor  Indicis.  H.  Wooden 
rod  with  hole,  K,  for  hand ;  D.  Iron-wire 
collar,  acting  through  B  on  an  axle,  N,  to 
which  a  lever  is  attached.  Seen  from  the 
end. 


surlace. 
41,  p.  176.) 

With  this  apparatus  one  can  study  (i)  The  force  of  contraction  ;  (2)  The 
effect  of  fatigue  and  recovery  ;  (3)  One  may  excite  the  muscle  by  means  of 
electricity  ;  (4)  One  may  compare  the  mechanical  response  elicited  by  electrical 
(tetanic)  and  tlie  normal  physiological  stimulus,  and  learn  that  during  a 
voluntary  contraction  there  is  a  greater  contraction,  i.e.,  a  greater  liberation 
of  energy  than  during  the  strongest  contraction  elicited  by  electrical  stimu- 
lation. 

2.  MoBso's  Ergograph  for  Fatigue  and  Work. — This  is  a  most  useful 
instrument  (fig.  154),  by  means  of  which  the  student  can  study  the  process  of 
fatigue  on  himself,  the  conditions  that  predispose  to  it,  and  the  process  of 
recovery,  as  well  as  the  effect  of  various  conditions  on  the  fatigue-curve.  By 
means  of  this  instrument  also  the  amount  of  work  done  is  recorded  graphic- 
ally, and  can  be  estimated  in  terms  of  kilogrammetres,  the  contractions  in 
this  case  being  isotonic.  The  forearm  is  fixed  by  means  of  clamps  upon  an 
iron  framework,  while  the  hand  also  is  firmly  fixed,  the  index  and  ring 
fingers  being  placed  in  brass  hollow  cylinders,  while  the  middle  finger  is  free. 
The  forearm  is  placed  in  a  half-supinated  position.  To  the  middle  finger  is 
attached  a  cord,  passing  to  the  writing-style,  and  to  the  latter  is  attached  a 
weight,  which  can  be  varied.  The  style  writes  upon  a  recording  drum 
moving  horizontally.  The  forearm  is  fixed  in  the  apparatus,  and  the  middle 
finger  attached  to  the  writing  apparatus,  and  to  the  latter  is  added  a  load  of 
known  weight,  6.7.,  2-3  kilos.  The  experimenter  flexes  the  middle  finger, 
lifts  the  load,  and  as  soon  as  the  contraction  is  over  the  load  extends  the 


XL  v.]  ELEGTKO-MOTIVE  PHENOMENA.  23 1 

finger.  The  exjierimenter  contracts  the  muscles,  moving  his  middle  finger 
at  a  given  rate,  say  once  every  two  seconds,  either  by  listening  to  the  beat  of 
a  metronome,  or  observing  the  motion  of  a  pendulum  vibrating  a  definite 
number  of  times  per  minute.  (A.  Mosso,  "Fatigue  of  human  muscle,"  Du 
Bois-Eeymond's  Archiv,  1S90,  and  Uie  Urmiidimg,  Leipzig,  1892  ;  Warren 
P.  Lombard,  "Some  of  the  influences  which  aff'ect  the  power  of  voluntary 
muscular  contraction,"  Journal  of  Fhysiology,  xiii.  i.) 


3.  Dynamograph. — Waller  has  devised  a  simple  fonn  of  this. 
To  the  vertical  arm  of  a  dynamometer  of  Salter  (p.  189),  a  strong 
steel  spring  with  a  long  recording  arm  is  attached,  the  record 
being  made  on  a  very  slow-moving  drum,  e.g.,  a  cylinder  placed 
vertically   on    the   hour-spindle    of    an   American   clock.      The 

iiynamograj)h  is  so  arranged  that  it  can  be  clamped  to  a  table.     The  observer, 

by  grasping  the  handles  of  the  instrument,  makes  a  series  of  maximal  efforts. 

say  30  per  minute, —i.e. ,  each  lasting  two  seconds, — then  he  takes  one  minute's 

rest,  and  repeats  the  experiment. 

In  this  way  one  can  measure  the  muscular  strength  and  how  it  declines 

with  each  contraction  or  series  of  contractions,  together  with  its  recovery 

during  rest.     We  have  a  series  of  isometric  contractions. 


LESSON  XLV. 

DIFFERENTIAL.  ASTATIC  GALVANOMETER— NON- 
POLARISABLB  ELECTRODES-SHUNT-DEMAR- 
CATION AND  ACTION-CURRENTS   IN  MUSCLE. 

ELECTRO-MOTIVE  PHENOMENA  OF  MUSCLE 
AND  NERVE. 

1.  Thomson's  High-Resistance  Differential  Astatic  Galvano- 
meter. 

(a.)  Place  the  galvanometer  (fig.  155)  upon  a  stand  unaffected 


232 


PRACTICAL  PHYSIOLOGY. 


[XLV. 


"by  vibrations,  e.g.y  on  a  slate  slab  fixed  into  the  wall,  or  on  a  solid 
stone  pillar  fixed  in  the  earth,  taking  care  that  no  iron  is  near. 

(h.)  Let  the  galvanometer  face  wef^t^  ?.e.,  with  the  plane  of  the 
coils  in  the  magnetic  meridian,  the  magnetic  meridian  being  ascer- 
tained by  means  of  a  magnetic  needle.  As  the  galvanometer  is  a 
differential  one,  to  convert  it  into  a  single  one,  connect  the  two 


FlO.  156.— Lamp  and  Scale  for  Iliom- 
Bon's  Galvanometer. 


Fio.  155.— Sir  William  Thomson's  Re- 
flecting Galvanometer,  u.  Upper, 
I.  Lower  coil ;  «,  «.  Levelling  screwB ; 
m.  Magnet  on  a  brass  support,  b. 


FlQ.  157.  —  Non- 
Polarisable  Elec- 
trodes. Z.  Zincs; 
K.  Cork ;  a.  Zinc 
sulphate  solu- 
tion;  t,  t.  Claj 
points. 


central  binding  screws  on  the  ebonite  base  by  means  of  a  copper 


wire. 


(c.)  Ey  means  of  the  three  screws  level  the  galvanometer. 

('/.)  Take  off  the  glass  cover  and  steadily  raise  the  small  milled 
head  on  the  top  of  the  upper  coils,  which  frees  the  mirror,  and 
allows  it  to  swing  free.     Replace  the  glass  shade. 

(e.)  Place  the  scale  (fig.  156)  also  in  the  magnetic  meridian  and 


XLV.]  ELECTRO-MOTIVE   PHENOMENA.  233 

I  metre  from  the  mirror,  taking  care  that  it  is  at  the  proper  height. 
Instead  of  a  slit  in  the  scale,  it  is  better  to  fix  in  it  a  thin  wire,  and 
by  means  of  a  lens  of  short  focal  distance  to  bring  the  image  of  the 
wire  to  a  focus  in  the  middle  of  the  illuminated  disc  of  light 
reflected  from  the  mirror  upon  the  scale. 

(a'.)  Light  the  paraffin  lamp,  place  the  edge  of  the  flame  towards 
the  slit,  darken  the  room,  and  see  that  the  centre  of  the  scale,  its 
zero,  the  slit  in  the  scale,  the  flame  of  the  lamp,  and  the  centre  of 
the  mirror,  are  all  in  the  same  vertical  plane,  so  that  a  good  light 
is  thrown  on  the  mirror  in  order  to  obtain  a  good  image  on  the 
scale. 

{g.)  Make  the  needle  all  but  astatic  by  means  of  the  magnet 
attached  to  the  bar  above  the  instrument.  The  needle  is  most 
sensitive  when  it  smngs  slowly. 

(h.)  Test  the  sensitiveness  of  the  galvanometer  by  applying  the 
tips  of  two  moist  fingers  to  the  two  outer  binding  screws  of  the 
instrument,  when  at  once  the  beam  of  light  passes  off  the  scale. 

2.  Non-Pol arisable  Electrodes.— One  may  use  the  old  form 
of  Du  Bois-Reymond,  the  simple  tube  electrodes,  or  the  "brush 
electrodes  «  of  Y.  Fleischl  (fig.  160). 

(A.)  (a.)  Use  glass  tubes  about  3  cm.  long  and  5  mm.  in  diameter, 
tapering  somewhat  near  one  end,  and  see  that  they  are  perfectly 
clean. 

(h.)  Plug  the  tapered  end  of  the  glass  tube  with  a  plug  of  china 
clay,  made  by  mixing  kaolin  into  a  paste  with  normal  saline. 
Push  the  clay  into  the  lower  third  or  thereby  of  the  tube  ;  plug 
the  latter,  using  a  fresh-cut  piece  of  wood  or  thin  glass  rod  to  do 
so  ;  allow  part  of  the  clay  to  project  beyond  the  tapered  end  of  the 
tube  (fig.  157,  ^,  t). 

(c.)  With  a  clean  pipette  half  fill  the  remainder  of  the  tube  with 
a  saturated  neutral  solution  of  zinc  sulphate.  Make  two  such 
electrodes. 

{d.)  Into  each  tube  introduce  a  well-amalgamated  piece  of  zinc 
wire  with  a  thin  copper  wire  soldered  to  its  upper  end  (Z,  Z),  fix 
the  electrodes  in  suitable  holders  in  a  moist  chamber,  and  attach 
the  wires  of  the  zincs  to  the  binding  screws  on  the  stage  of  the 
moist  chamber.     The  zinc  should  not  touch  the  clay. 

(B.)  Some  prefer  a  [J -shaped  glass  tube  held  in  a  suitable 
holder  attached  to  a  vulcanite  rod  in  the  moist  chamber 
(B.  Sanderson's  pattern).  The  tube  contains  a  saturated  solution  of 
zinc  sulphate  as  before.  Into  one  limb  of  the  tube  is  placed  the 
rod  of  amalgamated  zinc.  In  the  other  free  Hmb  is  placed  a 
straight  tube  with  a  slight  flange  at  its  upper  end  filled  with  kaolin 
moistened  with  normal  saline,  the  kaolin  projecting  as  a  cap  above 


234 


PRACTICAL   PHYSIOLOGY. 


[XLY. 


the  level  of  the   (J -shaped  tube.     The   muscle  is  placed   on  the 
two  corresponding  kaolin  caps. 

3.  Shunt. — This  is  an  arrangement  by  which  a  greater  or  lesa 
proportion  of  a  current  can  be  sent  through  the  galvanometer  (fig. 
158).  The  brass  bars  on  the  upper  surface 
are  marked  with  the  numbers  -g-,  -^V,  -g-^y^, 
indicating  the  ratio  between  their  resistance 
and  that  of  the  galvanometer,  so  that  when 
the  plug  is  inserted  in  the  several  positions, 


tV, 


ToTTj 


or 


000 


of  the  whole  current  may  be 


sent  through  the  galvanometer. 

4.  Muscle  Demarcation-Current  (Current 
of  Injury). 

{a.)  Arrange  the  apparatus  according  to  the 
scheme  (fig.  159). 

(b.)  Place  a  shunt  between  the  N.P.  elec- 
trodes and  the  galvanometer.  Connect  two 
wires  from  the  electrodes  to  the  binding 
screws  (A,  B)  of  the  shunt,  and  from  the  same  binding  screws 
attach  two  wires  to  the  galvanometer.     Insert  a  plug  (C)  between 


FlO.  158.- The  Shunt. 


FlO.  159.— Arrangement  of  Apparatus  for  the  Demarcation-Current  of  Muscle.  M.  Muscle 
on  a  glass  plate,  P ;  S.  Shuut ;  G.  Galvanometer ;  Mg.  Its  magnet  moved  by  the 
miUed  head,  m;  L.  and  Sc.  Lamp  and  scale. 

A  and  B,  thus  short-circuiting  the  muscle-current.  When  work- 
ing with  muscle,  keep  a  plug  in  the  hole  opposite  ^  on  the 
shunt.     Arrange  the  lamp  and  scale  so  as  to  have  a  good  image  of 


XLV.]  ELECTRO-MOTIVE   PHENOMENA.  235 

the  mirror  on  the  zero  of  the  scale  ;  adjusting,  if  necessary,  by 
means  of  the  magnet  moved  by  the  milled  head  on  the  top  of  the 
glass  shade  (fig.  159,  vi). 

((•.)  Test  the  electrodes,  either  by  bringing  them  together  or  by 
joining  them  with  a  piece  of  silk  thread  covered  with  china-clay 
paste.  After  removing  all  the  plugs  from  the  shunt,  there  ought  to 
be  no  deflection  of  the  spot  of  light.  If  there  is  none,  there  is  no 
polarity,  and  the  electrodes  are  perfect. 

(fl)  Ascertain  the  Direction  of  Current  in  Galvanometer. — 
]\rake  a  small  Smee's  battery  with  a  two-ounce  bottle.  Place  in  the 
bottle  dilute  sulphuric  acid  (i  :  20)  and  two  wires  of  zinc  (  -  )  and 
copper  ( + ),  with  wires  soldered  to  them.  Connect  them  with 
the  galvanometer.  Arrange  the  shunt  so  that  j^  or  -j-oW  P^^*' 
of  the  current  thus  generated  goes  through  the  galvanometer. 
Note  the  deflection  and  its  direction.  Arrange  the  N.P.  electrodes 
in  the  same  way,  and  observe  which  is  the  negative  and  which 
the  positive  pole  corresponding  to  the  zinc  and  copper  of  the 
battery. 

(e.)  Prepare  a  Muscle. — Dissect  out  either  the  sartorius  or 
eemi-membranosus  of  a  frog,  which  consist  of  parallel  fibres,  but 
avoid  touching  the  muscle  with  the  acid  skin  of  the  frog.  Lay 
the  muscle  on  a  glass  plate  or  block  of  paraffin  under  the  moist 
chamber. 

(f.)  Keep  one  plug  in  the  shunt  at  C,  to  short-circuit  the  elec- 
trodes, and  the  other  plug  at  ^.  Cut  a  fresh  transverse  section  at 
one  end  of  the  muscle,  and  adjust  the  point  of  one  electrode  exactly 
over  the  centre  (equator)  of  the  longitudinal  surface  of  the  muscle. 
Apply  the  other  electrode  exactly  to  the  centre  of  the  freshly 
divided  transverse  surface  (fig.  159). 

(g.)  Current  of  Injury. — Remove  the  skort-circuiting  plug,  C, 
from  the  shunt,  keep  one  plug  in  at  |^,  so  that  ^  of  the  total 
current  from  the  muscle  goes  through  the  galvanometer.  Note  the 
direction  and  extent  of  the  deflection.  By  noting  the  direction,  and 
from  the  observation  already  made  ((/),  one  knows  that  the  longi- 
tudinal surface  of  the  muscle  is  + ,  and  the  transverse  section  - . 
Replace  the  plug-key  (C),  and  allow  the  needle  to  come  to  rest  at 
zero.  The  deflection  was  caused  by  the  current  of  injury,  and  it 
flows  from  the  equator  or  middle  of  the  muscle  towards  the  cut 
ends.  It  is  also  called  tlie  demarcation-current.  The  injured  part 
of  a  muscle  is  negative  to  the  uninjured  part,  and  the  current  in  the 
galvanometer  is  from  the  longitudinal  ( + )  surface  to  the  injured 
negative  transverse  surface. 

(h.)  Bring  the  N.P.  electrode  on  the  longitudinal  surface  nearer 
to  the  end  of  the  muscle,  and  note  the  diminution  of  the  deflection 
of  the  needle.     Replace  plug  C. 


236 


PRACTICAL  PHYSIOLOQT. 


[XLV. 


(/.)  Vary  the  position  of  the 
electrodes  and  note  the  variation 
in  the  deflection.  If  they  be  equi- 
distant from  the  equator,  there 
is  no  deflection.  The  greatest 
deflection  takes  place  when  one 
electrode  is  over  the  equator  and 
the  other  over  the  centre  of  the 
transverse  section  of  a  muscle 
composed  of  parallel  fibres.  The 
deflection,  i.e.,  the  electro-motive 
force,  diminishes  as  the  electrodes 
are  moved  from  the  equator  or  the 
centre  of  the  transverse  section. 
In  certain  positions  no  deflection 
is  obtained. 

5.  Negative  Variation  of  the 
Muscle-Current. 

(a.)  Use  the  same 
muscle  preparation, 
or  isolate  the   gas- 
trocnemius       with 
the    sciatic    nerve 
attached.       Divide 
the    muscle    trans- 
versely, and  lay  the 
artificial  transverse 
section  on  one  elec- 
trode, and  the  longi- 
tudinal surface  on 
the      other.       Ob- 
serve the  extent  of 
the  deflection. 
{h.)  Adjust   an  induction   coil 
for  repeated  shocks,  placing  it  at 
some  distance  from  the  galvano- 
meter. 

{c.)  Take  the  demarcation- 
current,  observing  the  deflection, 
and  allow  the  spot  of  light  to 
take  up  its  new  position  on 
the  scale.  Tetanise  the  muscle 
through  its  nerve,  and  observe 
that    the   spot   of    Ught    travels 


Fig.  160.— Brush 
Electrodes  of 
V.  Fleischl. 


XLVI.]  NERVE-CURRENTa  237 

towards  zero.  This  is  the  "negative  variation  of  the  muscle- 
current."  If  the  gastrocnemius  be  used,  stimulate  the  sciatic  nerve. 
Care  must  be  taken  that  the  muscle  does  not  shift  its  position  on  the 
electrodes.  According  to  Hermann's  theory,  it  is  brought  about  as 
follows : — An  injured  part  of  a  muscle  (or  nerve)  is  negative  to  an 
uninjured  part — 'negativity  of  injury,"  and  similarly  an  active 
part  of  a  muscle  is  negative  to  an  inactive  part — "negativity  of 
activity."  The  demarcation-current  or  injury-current  passing  in 
the  galvanometa.'from  the  longitudinal  +  to  the  transverse  -  surface 
is  diminislied,  because,  when  the  muscle  contracts,  there  is  a  current 
set  up — action-current — in  the  opposite  direction,  which  diminishes 
the  total  current  acting  on  the  galvanometer. 


ADDITIONAL  EXERCISEa 

6.  Brush  Electrodes  of  V.  Fleischl  (fig.  160)  consist  of  glass  tubes  5  mm. 
in  diameter  and  4  cm.  long.  Into  one  end  is  fitted  a  perfectly  clean  camel's- 
hair  pencil,  and  into  the  other  dips  a  well-amalgamated  rod  of  zinc  with  a 
binding  screw  at  its  free  end.  Place  some  clay  in  the  lower  part  of  the  tube, 
and  then  fill  it  with  a  saturated  solution  of  zinc  sulphate.  A  piece  of  india- 
rubber  tubing  fits  as  a  cap  over  the  upper  end  of  the  glass  tube.  The  brushes 
are  moistened  with  a  mixture  of  kaolin  and  normal  saline. 

7.  D'Arsonval's  Non-Polarisable  Electrodes  (fig.  161).— The  electrodes 
consist  of  a  silver  wire  coated  with  fused  silver  chloride.  The  silver  wire  is 
held  in  a  suitable  stand,  while  the  silver  chloride  coated  part  is  placed  in  a 
tube  tapering  to  a  point  below  and  filled  with  normal  saline.  At  the  lower 
tapered  end  there  is  a  small  aperture  into  which  is  introduced  a  thick  thread. 
The  tube  is  closed  above  with  a  cork  (C),  through  which  passes  the  silvei 
electrode  (A).  The  tapered  points  are  brought  into  contact  with  the  tissues. 
They  should  be  kept  in  the  dark. 

Vertical  Electrodes  of  Fick, — Into  a  vertical  glass  tube  the  amalgamated 
zinc  is  introduced  from  below,  the  tube  is  filled  with  a  saturated  solution  of 
ZnS04,  but  the  nerve  rests  on  a  hammer-shaped  piece  of  baken  porcelain, 
such  as  is  used  for  porous  cells  for  batteries.  It  is  soaked  with  salt  solution, 
and  has  a  process  which  dips  into  the  zinc  sulphate.  Several  of  these  can  be 
arranged  side  by  side  in  a  suitable  holder. 


LESSON  XLVL 


NERVE  -  CURRENTS  —  ELECTRO  -  MOTIVE  PHENO- 
MENA OP  THE  HEART— CAPILLARY  ELECTRO- 
METER. 

1.  Demarcation-Current  of  Nerve. 

(a.)  Render  the  galvanometer  as  sensitive  as  possible  by  adjusting  at  a  suit- 
able height  the  north  pole  of  the  magnet  over  the  north  pole  of  the  uppei 
needle. 


238 


PRACTICAL  PHYSIOLOGY. 


[XLVL 


(6.)  Prepare  N.P.  electrodes  for  a  nerve.  In  this  case  the  electrodes  are 
hook-shaped,  and  one  is  adjusted  over  the  other.  The  upper  hooked  electrode 
has  a  groove  on  its  concavity  communicating  with  the  interior  of  the  tube 
(fig.  162).     Place  only  one  plug  in  the  shunt  between  A  and  B. 

(c. )  Dissect  out  a  long  stretch  of  the  sciatic  nerve,  make  a  fresh  transverse 
section  at  both  ends,  hang  it  over  the  upper  N.P.  electrode  (N),  and  resting 
with  its  two  cut  ends  on  the  lower  electrode  (C),  thus  doubling  the  strength 
of  the  current  (fig.  162). 

[d.)  Remove  the  plug  from  C  in  the  shunt  and  pass  the  whole  of  the  de- 
marcation nerve-current  through  the  galvanometer,  noting  the  deflection. 

(e.)  Instead  of  adjusting  the  nerve  as  in  {c),  it  may 
be  so  placed  on  the  ordinary  tube  N.P.  electrodes  that 
the  cut  end  rests  on  one  electrode  and  the  longitudinal 
surface  on  the  other,  thus  leaving  part  of  the  nerve  fi'ee. 
Observe  the  deflection  in  this  way. 

2.  Action-Current  of  Nerve. 
(a.)  Observe  the  amount  of  deflection  as  in  (1.  «.). 

Stimulate  with  an  interrupted  current  the  free  end  ol 
the  nerve,  and  observe  that  the  spot  of  light  travels 
towards  zero.  This  was  formerly  called  the  **  negative 
variation  "  of  the  nerve-current. 

3.  Electro-Motive  Phenomena  of  the  Heart. — The 
arrangement  of  the  apparatus  is  the  same  as  in  Lesson 
XLV. 

{a.)  Make  a  Stannius  preparation  of  the  heart,  using 
only  the  first  ligature  (Lesson  LV.  1)  to  arrest  the 
heart's  action.  Lead  off"  with  brush  N.P.  electrodes 
fi-om  base  and  apex  of  the  quiescent  uninjured  heart ; 
there  is  no  deflection. 

(b.)  Pinch  the  apex  so  as  to   injure  it;   it  becomes 
negative  ;  a  diff"erence  of  potential  is  at  once  set  up  and 
now  the  spot  of  light  oscillates  with  each  beat  of  the  heart. 

(c. )  Excise  a  heart  so  as  to  get  a  spontaneously  beating  ventricle  ;  lead  off 
from  the  base  and  apex  of  the  latter  ;  observe  the  so-called  "  negative  varia- 
tion "  with  each  contraction. 

(cl.)  See  also  Lesson  XLVII.  6  for  secondary  contraction  excited  by  the 
beating  heart. 


FlO.  162.— Nerve  N.P, 
Electrodes.  N.  Nerve 
C.  Clay  of  electrodes 
Zn.  Zincs, 


4,  Capillary  Electrometer. 

(a.)  Lead  off"  a  muscle  to  the  two  binding  screws  of  a  capillary  electrometer. 
The  fine  thread  of  mercury  must  be  observed  with  a  microscope. 

By  means  of  the  capillary  electrometer  Waller  has  shown  the  diphasic 
variation  of  the  heart-current  in  man  and  in  a  living  dog. 


XLVII.] 


GALVANIS   EXPERIMENT. 


239 


LESSOK  XLVIL 

GALVANI'S  EXPERIMENT— SECONDARY  CONTRAC- 
TION  AND  TETANUS  —  PARADOXICAL  CON- 
TRACTION—KtTHNE'S  EXPERIMENTS. 


1.  Galvani's  Experiment. 

(a.)  Destroy  the  brain  of  a  frog,  divide  tke  spine  aboi>t  tlie 
middle  of  the  dorsal  region,  cut  away  the  upper  part  of  the  body, 
and  remove  the  viscera.  Remove  the  skin  from  the  hind-legs,  divide 
the  iliac  bones  and  urostyle,  avoid  injuring  the  lumbar  plexus, 
which  will  remain  as  the  only  tissue  con- 
necting the  lower  end  of  the  vertebral 
column  with  the  legs.  Thrust  an  S-shaped 
copper  hook  through  the  lower  end  of  the 
spine  and  spinal  cord  (fig.  163). 

(b.)  Hook  the  frog  to  an  iron  tripod. 
Tilt  the  tripod  so  that  the  legs  come  in 
contact  with  one  of  the  legs  of  the  tripod ; 
vigorous  contractions  occur  whenever  the 
frog's  legs  touch  the  tripod. 

(c.)  With  the  frog  hanging  perpendicu- 
larly without  touching  the  tripod,  make  a 
U-shaped  piece  of  wire  composed  of  a 
copper  and  zinc  wire  soldered  together. 
Touch  the  nerves  above  with  the  copper 
(or  zinc)  end,  and  the  muscles  below  with 
the  zinc  (or  copper),  when  contraction  occurs  at  make,  or  break, 
or  both. 


Fig.  163.— Galvani's 
Experiment. 


2.  Contraction  without  Metals. 

(a.)  Make  a  fresh  nerve-muscle  preparation,  leaving  the  leg 
attached  to  the  femur,  and  having  the  sciatic  nerve  as  long  as  possible. 
Hold  the  femur  in  one  hand,  lift  the  nerve  on  a  camel's-hair  pencil  or 
glass  rod  moistened  with  normal  sahne,  and  allow  it  to  fall  upon  the 
gastrocnemius,  when  the  muscle  will  contract.  Contraction  occurs 
because  the  nerve  is  suddenly  stimulated,  owing  to  the  surface  of 
the  muscle  having  different  potential-s. 

{/>.)  Or  remove  the  skin  from  the  hind  legs  of  a  frog,  and  dissect 
out  the  sciatic  nerve  in  its  whole  extent.  Divide  it  at  its  upper 
end.  If  the  nerve  be  lifted  on  a  glass  rod  and  allowed  to  fall 
longitudinally  on  the  triceps  muscle  there  is  no  contraction. 


240  PRACTICAL  PHYSIOLOGY.  [XLVIL 

Make  a  transverse  cut  across  the  triceps,  and  so  arrange  the 
nerve  that  its  cut  end  rests  on  the  transverse  section  of  the 
muscle,  and  its  longitudinal  surface  on  the  longitudinal  surface  of 
the  muscle.  As  soon  as  this  interval  is  bridged  over,  the  leg  muscles 
contract. 

There  is  a  large  difference  in  potential  between  the  transversely- 
cut  muscle  and  its  longitudinal  surface — there  is  a  "  muscle-current  " 
in  the  muscle  from  the  artificial  transverse  section  to  the  longitudinal 
surface,  so  when  the  nerve  bridges  over  these  surfaces,  there  is  an 
external  derivation-current  passing  in  the  nerve,  whereby  the  latter 
is  stimulated. 

Thus  the  "physiological  ''heoscope"  is  used  to  show  the 
presence  of  electrical  currents  in  muscle  under  certain  conditions. 

3.  Secondary  Contraction  or  Twitch  and  Secondary  Tetanus. 

(a.)  Arrange  an  induction  coil  for  single  make  and  break  shocks. 
Make  two  nerve-muscle  preparations. 

{/j.)  Place  the  left  sciatic  nerve  (A)  over  the  right  gastrocnemius 
(B)  or  thigh  muscles,  and  the  right  sciatic  nerve  over  the  electrodes 
(E)  (fig.  164). 

('•.)  Stimulate  the  nerve  of  B  with  single  induction  shocks — the 
muscles  of  both  B  and  A  contract.     The  contraction  in  A  is  called 

a  secondary  contraction.  A  is  the 
rheoscopic  limb  as  by  its  contraction  it 
shows  the  existence  of  an  electrical 
current  in  B.  When  B  contracts, 
there  is  a  sudden  diminution  of  its 
muscle-current,  which  circulates  in  the 
nerve  of  A.  This  sudden  diminution 
— negative  variation — is  tantamount 
to  a  stimulus,  and  so  the  nerve  of  A 
is  stimulated. 

(d.)  Arrange  the  induction  coil  for 
repeated  shocks,  and  stimulate  the 
nerve  of  B.  B  is  tetanised,  and  so  is 
A  simultaneously.  This  is  secondary 
f  la.  i64.-Secondary  Contraction,  tetanus.  The  nerve  of  A  is  stimulated 
by  the  sudden  series  of  negative  varia- 
tions of  the  muscle- current  during  the  contraction  of  B.  So  that 
the  electrical  change  during  tetanus  is  interrupted  and  not  con- 
tinuous like  the  change  in  form  of  the  muscle,  and  with  50  shocks 
per  second  each  electrica'  chang?  must  reach  its  maximum  and 
subside  in  y^". 

(e.)  Ligature  the  nerve  of  A  near  the  muscle,  stimulate  the  nerve 
of  B ;  there  is  no  contraction  of  A  although  B  contracts. 


XLVII.] 


SECONDARY   CONTRACTION. 


241 


(/. )  Prepare  another  limb  and  adjust  it  in  place  of  A,  ligature  the  nerve  of 
B.  On  stimulating  the  nerve  of  B,  no  contraction  takes  place  either  in  A  or 
B. 

4.  Secondary  Contraction  from  Nerve. 

(a.)  Make  a  nerve- muscle  preparation  and  place  it  on  a  glass 
plate  (B).  Dissect  out  the  sciatic  nerve  of  the  opposite  side  (A). 
Lay  I  cm.  of  the  isolated  sciatic  nerve  (A)  on  a  similar  length  of 
the  nerve  of  the  nerve-muscle  preparation  (B)  (fig.  165). 

(b.)  Stimulate  A  with  a  single  induction  shock ;  the  muscle  of 
B  contracts.  Stimulate  A  with  an  interrupted  current ;  the  muscle 
of  B  is  thrown  into  tetanus. 

(c.)  Ligature  A  and  stimulate  again.  B  does  not  contract. 
Therefore  its  contraction  was  not  due  to  an  escape  of  the  stimulating 
current.  The  "  secondary  contractions  "  in  B  are  due  to  the  sudden 
variations  of  the  electro-motivity  produced  in  A  when  it  is  stimu- 
lated. 


Fio.  165.— Scheme  of  Secondary 

Contraction. 


WlQ.  166. — Scheme  of  Paradoxical 
Contraction. 


5.  Paradoxical  Contraction. 

(a.)  An'angement. — Arrange  a  Daniell's  cell  and  key  for  giving 
a  galvanic  current,  or  use  repeated  induction  shocks. 

(b.)  Pith  a  frog,  expose  the  sciatic  nerve  down  to  the  knee  (fig. 
166,  S).  Trace  the  two  branches  into  which  it  divides.  Divide 
the  outer  or  peroneal  branch  as  near  as  possible  to  the  knee,  and 
stimulate  its  central  end  (P)  by  a  faradic  current.  A  certain 
strength  of  current  will  be  found  whereby  the  muscles  supplied  by 
the  other  division  of  the  nerve  are  thrown  into  tetanus  (T).  The 
tibial  nerve  to  the  gastrocnemius  is  stimulated  by  escape  or  spread 
of  "  electrotonic  "  currents  from  the  excited  nerve. 


242  PRACTICAL   PHYSIOLOGY.  [XLVIL 

(f.)  Instead  of  induction  shocks,  use  a  shock  from  a  Darnell's 
cell.     There  is  a  paradoxical  twitch. 

'No  paradoxical  response  is  produced  hy  stimulation  other  than 
electrical  stimuli,  e.g.,  section  of  a  nerve,  salt.  It  is  still  produced 
even  if  the  peroneal  nerve  be  ligatured  on  the  central  side  of  the 
seat  of  stimulation. 

6.  Frog's  Heart-Current  (Secondary  contraction). 

(a.)  Injured  Heart. — A  quiescent  uninjured  heart  gives  no 
current,  but  an  active  heart  does,  and  so  does  an  injured  one.  The 
action-current  of  an  injured  heart  is  easily  shown  when  a  nerve  of 
a  nerve-muscle  preparation  is  placed  on  a  beating  rabbit's  heart 
inside  the  thorax.  In  the  frog,  it  requires  some  care  to  show  this. 
It  is  easy,  however,  to  obtain  a  secondary  contraction  from  a 
beating  injured  frog's  heart. 

Prepare  a  nerve-muscle  preparation  or  rheoscopic  limb.  Excise 
the  heart  of  a  pithed  frog,  and  place  it  on  a  dry  glass  plate,  removing 
the  surplus  blood.  Cut  off  the  apex  of  heart,  and  to  it  apply  the 
transverse  section  of  the  divided  sciatic  nerve,  letting  a  part  of 
the  longitudinal  surface  of  the  nerve  rest  on  the  uninjured  ventricle. 
AVith  each  beat  of  the  heart  there  is  a  twitch  of  the  rheoscopic 
limb  or  muscle. 

(6.)  Action-Cun-ent  of  Uninjured  Frog's  Heart. — On  placing  the 
nerve  of  a  nerve-muscle  preparation  along  the  exposed  frog's  heart 
from  apex  to  base,  one  sometimes  gets  a  muscular  response  to  each 
beat  of  the  heart,  but  the  experiment  does  not  always  succeed. 
It  is  easier  to  do  it  on  a  Stanniused  heart ;  with  each  contraction 
of  the  heart  excited  artificially,  there  is  a  secondary  contraction. 


ADDITIONAL  EXERCISES. 

7.  Kiihne's  Nerve-Current  Experiment. 

(a.)  Invert  an  earthenware  bowl  (B),  and  with  wax  fix  to  its  base  a  piece  of 
glass  lo  cm.  square  (fig.  167,  G.. 

{h.)  Make  two  rolls  of  kaolin  (moistened  with  normal  saline^,  about  i  cm. 
in  diameter  and  6  cm.  in  length  (P,  P'),  bend  them  at  a  right  angle,  and 
hang  them  over  the  glass  plate  about  6  mm.  apart. 

(f. )  Make  a  nerve-muscle  preparation,  lay  the  muscle  on  the  glass  plate, 
and  the  nerve  (N   over  the  rolls  of  china  clay. 

(rf.)  Fill  a  small  glass  vessel  iC'  with  normal  saline,  and  allow  the  two 
fiee  ends  of  the  clay  to  dip  into  it.  With  each  dip  the  muscle  contracts.  In 
this  case  the  nerve  is  stimulated  by  the  completion  of  the  circuit  of  its  own 
demarcation-current,  and  this  in  turn  indirectly  stimulates  the  muscle, 

8.  Kiihne's  Muscle-Press — Secondary  Contraction  from  Muscle  to  Muscle. 
— Pre2)are  t^o  sartorius  muscles  of  a  frog.     Place  the  end   of  one  muscle 


XLVIII.] 


ELECTROTONUS. 


243 


over  the  end  of  the  other,  both  muscles  being  in  line  with  each  other,  and 
the  overlapj)ing  i)ortion  so  arranged  that  they  can  be  pressed  togetlier  by 
means  of  the  small  screw-press  devised  by  Kiihne  for  this  i)urpose. 

On  stimulating — by  electrical,  chemical,  or  other  stimuli — the  free  end  of 
either  muscle,  so  as  to 
cause  that  muscle  to  con- 
tract, the  second  muscle 
also  contracts.  The  nega- 
tive variation  of  the 
muscle-current  stimulates 
the  second  muscle.  This 
result  does  not-  take  place 
if  a  thin  layer  of  tinfoil 
be  placed  between  the  two 
muscles. 


Fig.  167.— Kiihne's  Experiment 

•iv.  Nerve  on  P,  P',  Pads  of  clay 


B.  Bowl ;  O.  Glass  plate 
C.  Capsule. 


9.  Biedermann's  Modi- 
fication of  Secondary 
Muscular  Contraction. — 
If  a  frog  be  denuded  of  its 
skin  and  left  exposed  to 
the    air    for     twenty-four 

hours — the  time  varying  with  the  temperature,  amount  of  moisture  in  the  air, 
&c. — on  causing  one  muscle  to  contract,  other  muscles  contract  secondarily. 
On  placing  the  two  sartorius  muscles  in  direct  contact  with  each  other,  when 
one  muscle  is  made  to  contract,  the  other  does  so  secondarily  without  the  use 
of  a  muscle-press. 


LESSON  XLVIII. 


ELECTROTONUS— ELECTROTONIC  VARIATION 
OF  THE  EXCITABILITY. 


Electrotonus. — When  a  nerve  is  traversed  by  a  constant 
current,  its  so-called  "  vital "  properties  are  altered,  i.e.,  its  excita- 
bility, conductivity,  and  electro-motivity.  The  region  of  the 
nerve  affected  by  the  positive  pole  is  said  to  be  in-  the  anelectro- 
tonic,  and  that  by  the  negative  in  the  kathelectrotonic  condition. 
Therefore  we  have  to  study  the — 

I.  Electro-motive  alteration  of  the  excitahility  and  conductivity. 

II.  Electro-motive  alteration  of  the  electro-motivity, 

1.  Electrotonic  Variation  of  the  Excitability. 

A.  (a.)  Connect  two  small  Grove's  cells  or  two  Danieil's  to  a 
Pohl's  commutator  with  cross-bars  (fig.  168),  introducing  a  Du  Bois 
key  to  short-circuit  the  battery.  From  two  of  the  binding  screws 
connect  wires  with  two  N.P.  electrodes  or  the  platinum  electrodes 
of  Du  Bois,  introducing  a  short-circuiting  key  in  the  electrode 
circuit  (fig.  168). 


244 


PRACrriCAL   PHYSIOLOGY. 


[xLvni. 


(b.)  Make  a  nerve-miiycle  preparation,  attach  a  straw  flag  to  the 
foot,  and  fix  the  femur  in  a  clamp,  as  in  fig.  i68.  Lay  the  nerve 
over  the  electrodes.  Trace  the  direction  of  the  current,  and  make 
a  mark  to  guide  you  as  to  when  the  current  in  the  nerve  is 
descending  or  ascending,  i.e.,  whether  the  negative  or  positive  pole 
is  next  the  muscle. 

(c.)  Place  a  drop  of  a  saturated  solution  of  common  salt  on  the 
nerve  between  the  electrodes  and  the  muscle.     In  a  minute  or  less 


Fia.  i68.— Scheme  of  Electrotonic  Variation  of  Excitability.    D.  Drop  of  strong  solution 
of  salt  on  the  nerve,  N ;  F.  Flag  on  the  muscle. 

the  toes  begin  to  twitch,  and  by-and-by  the  muscles  of  the  leg 
become  tetanic,  so  that  the  flag  is  raised  and  kept  in  the  horizontal 
position. 

((L)  Turn  the  commutator,  so  that  the  positive  pole  is  next  the 
muscle ;  the  straw  sinks,  i.e.,  the  excitability  of  the  nerve  in  the 
region  of  the  positive  pole  is  so  diminished  as  to  "  block  "  the 
impulse  passing  to  the  muscle,  showing  that  the  positive  pole 
lowers  the  excitability. 


FlO.  169. — Scheme  of  Electrotonic  Variation  of  Excitability.    P,  P.  Polarising, 
and  JS,  E.  Stimulation  current. 


(e.)  Reverse  the  commutator,  so  that  the  negative  pole  is  next 
the  muscle.  The  hmb  becomes  tetanic,  the  negative  pole 
{kathelectrotonic  area)  increases  the  excitability. 

2.  Another  Method.— Apparatus.— Three  Daniell's  cells,  two  pairs  of  N.P. 
electrodes,  two  Du  Bois  keys,  a  spring-key,  commutator  with  cross-bars, 
induction  coil,  wires,  moist  chamber,  drum. 

B.  (a.)  Arrange  the  apparatus  according  to  the  scheme  (fig.  169).  Prepare 
two  pairs  of  N.P.  electrodes  for  the  nerve. 


XLVIII.]  ELECTROTONUS.  245 

{/'.)  Connect  two  Daniell's  cells  with  a  Pohl's  commutator  with  cross-bars 
(C)  ;  connect  the  commutator — a  short-circuiting  key  intervening— to  one 
pair  of  the  N.P.  electrodes.     This  is  the  "polarising  current"  (P,  P). 

(f.)  Arrange  an  induction  coil  for  tetanising  shocks  ;  use  N.P.  electrodes 
and  short-circuit  the  secondary  circuit.  This  is  the  "exciting  current" 
(E,  E). 

{d. )  Make  a  nerve-muscle  preparation  with  the  nerve  as  long  as  possible, 
and  arrange  it  to  write  on  a  drum.  Place  the  nerve  on  the  two  pairs  of 
electrodes  in  the  moist  chamber,  the  "polarising"  pair  being  next  the  cut 
end  of  the  nerve  (P,  P),  and  about  i  centimetre  apart.  Between  the  polarising 
})air  and  the  muscle  apply  the  "exciting"  pair  of  electrodes  to  the  nerve 
(E,  E). 

(c.)  With  the  polarising  current  short-circuited,  pull  away  the  secondary 
from  the  primary  coil,  and  find  the  minimum  distance  at  which  a  feeble  con- 
traction of  the  muscle  is  obtained.  Push  the  secondary  coii  up  until  a  weak 
contraction  is  obtained,  and  take  a  tracing.  Previously  arrange  the  com- 
mutator to  send  a  descending  current  through  the  nerve.  While  the  muscle 
is  contracting  feebly,  throw  in  the  descending  polarising  current ;  at  once  the 
contraction  becomes  much  stronger.  Reverse  the  commutator  to  send  an 
ascending  polarising  current  through  the  nerve,  and  the  contraction  will 
cease. 


FlO.  170. — Tracinoj  showing  effect  of  Anode  and  Kathode  on  Excitability  of  Nerve,  the 
latter  stimulated  with  repeated  shocks.    T.  Time  in  seconds. 

(/.)  Repeat  the  experiment,  using  NeePs  hammer,  selecting  a  strength  of 
stimulus  just  insufficient  to  give  tetanic  response  when  the  +  pole  of  the  polar- 
ising current  is  next  the  muscle.  Reverse  the  commutator,  and  at  once  the 
previously  inadequate  shocks  become  adequate  and  tetanus  results  as  shown 
in  lig.  170,  where  the  effect  of  +  and  -  poles  are  shown  alternately. 

In  tlie  first  case,  the  area  influenced  by  the  exciting  electrodes  was  affected 
by  tlie  negative  pole,  i.e.,  was  in  the  condition  of  kathelectrotonus,  and  the 
tetanus  was  increased  ;  therefore,  the  kathelccfrotonic  condition  increascH  the 
excitability  of  a  nerve.  In  the  second,  the  nerve  next  the  exciting  electrodes 
yas  in  the  condition  of  anelectrotonus,  and  the  contractions  ceased  ;  therefore, 
tlie  anelectrotonic  condition  diminishes  the  excitability  of  a  nerve  (fig.  171). 

3.  Rheochord  —use  salt  as  stimulus. — The  experiment  may  also  be  done  by 
using  a  rheochord  to  graduate  the  polarising  current,  salt  again  being  used  as 
the  stimulus. 

{a.)  Arrange  two  N.P.  electrodes  in  a  moist  chamber,  provided  with  a 
recording  lever,  placing  the  N.P.'s  about  i  cm.  apart. 

(b.)  Connect  the  terminals  of  two  Daniell's  cells  (arranged  in  circuit)  to  the 
central  screws  of  a  Pohl's  commutator  (with  cross-bars)  as  in  tig.  172,  ]»lacing 
a  mercury  key  in  the  circuit.     Connect  th'e  wires,  x,  y,  to  the  two  blocks  on 


246 


PRACTICAL   PHYSIOLOGY. 


[XLVIII. 


the  rheochord  shown  in  fig.  92.  By  reversing  the  commutator  the  current 
through  the  rheochord  can  be  reversed.  Then  connect  one  N.P.  electrode  with 
one  terminal  of  the  rheochord,  while  the  other  N.P.  is  connected  with  the 
movable  block  or  slider  (S)  of  the  rheochord. 

(c.)  Notice  which  pole  is  next  the  muscle  according  to  the  position  of  the 
commutator  and  make  a  mark  to  guide  you.  Make  a  long  nerve-muscle  and 
arrange  it  over  the  electrodes,  attaching  the  muscle  to  a  recording  lever 
(crank). 


A 

+ 


K 


e    a 


i 


Fro.  171.— Scheme  of  Electrotonic  Variation  of  Excitability  in  a  Nerve.  K.  Kathode ; 
A.  Anode  ;  iV,  n.  Nerve.  The  cuive  above  the  line  indicates  increase,  and  that  below 
the  line  decrease  of  excitability. 


{d.)  Begin  with  the  slider  (S)  close  up  to  the  zero  terminal,  and  gradually 
slide  it  along  until,  on  closing  the  battery  circuit,  the  muscle  responds  at  make 
whether  the  +  or  -  pole  is  next  the  muscle,  i.e.,  whether  the  current  is 
ascending  or  descending. 

(e.)  Open  the  circuit,  place  on  the  nerve  near  the  muscle  either  a  drop 
of  saturated  solution  of  common  salt  or  fine  moist  crystals  of  salt.  Wait  till 
the  salt  produces  occasional  short  spasmodic  movements  of  the  limb.  Close 
the  key,  place  the  -  pole  next  the  muscle,  at  once  the  limb  becomes  tetanic 
owing  to  the  increase  of  excitability  under  the  influence  of  the  -  pole  {kath- 
electrotonus).    Open  the  current,  the  limb  becomes  quiescent. 

if.)  Open  the  key,  and 
after  a  short  time,  when 
the  spasms  reappear, 
reverse  the  commutator 
so  that  the  +  pole  is  next 
the  muscle.  Close  the 
current,  the  limb  becomes 
quiescent,  due  to  the  fall 
of  excitability  under  the 
influence  of  "the  +  pole 
[aneledrotoniis).  Break 
the  current,  the  muscle 
becomes  tetanic.  Thus  it 
is  shown  that  the  appear- 
ance of  kathelectrotonus  and  the  disappearance  of  anelectrotonus  are  accom- 
panied by  increase  of  excitability,  while  the  disappearance  of  kathelectrotonus 
and  the  appearance  of  anelectrotonus  are  accompanied  by  diminution  of 
excitability. 


Flo.  172.— Pohl's  Commutator  with  cross-bars,  arranged 
for  reversing  the  direction  of  a  current. 


XLIX.] 


PFLUGEKS   LAW   OF   CONTRACTION. 


247 


4.  Conductivity  is  impaired  in  the  Intra-Polar  Region.  -Arrange  the 
experiment  as  in  3,  but  place  the  salt  on  the  nerve  as  far  as  possible  from  the 
muscle.  When  the  salt  causes  tetanic  spasms,  close  the  current  through  the 
electrodes,  and  whether  this  current  be  ascending  or  descending,  the  spasms 
cease,  because  the  excitatory  change  is  "  blocked  "  in  the  intra-polar  area. 


LESSON  XLIX. 

PPLUGER'S  LAW  OP  CONTRACTION— ELECTRO- 
TONIC  VARIATION  OP  THE  ELECTRO- 
MOTIVITY— RITTER'S  TETANUS. 

1.  Pfliiger's  Law  of  Contraction.  —  Apparatus.  —  Several 
Daniell  or  small  Grove  cells,  commutator  with  cross-bars,  Du 
Bois  and  Hg-key,  rheochord,  N.P.  electrodes,  moist  chamber,  wires, 
recording  apparatus. 

(a.)  Arrange  the  apparatus  as  in  the  scheme  (fig.  173).  Connect 
two  Daniell  or  small  Grove  cells  to  a  Pohl's  commutator  ivith  cross- 


Fia.  173.— Scheme  for  Pfluger  s  Law.    R.  Rheochord  ;  B.  Battery  ;  C.  Commutator ; 
E.  Mercury  key  ;  K'.  Du  Bois  key  ;  E.  N.P.  Electrodes ;  iV.  Nerve. 


barSj  and  introduce  a  mercury  key  (K)  into  the  circuit :  connect 
the  commutator  with  the  rheochord  (R).  O-vunect  the  rheochord 
with  N.P.  electrodes,  introducing  a  short-circuiting  key.  Fix  to  a 
recording  lever  a  nerve-muscle  preparation — with  a  long  nerve — in 
the  moist  chamber,  and  lay  the  nerve  over  the  electrodes. 

{b.)  Begin  with  all  the  plugs  in  position  in  the  rheochord  and 
the  slider  hard  up  to  the  brass  blocks.  Place  the  commutator  to 
give  an  ascending  current,  make  and  break  the  current — gradually 
adjusting  the  slider  — until  a  contraction  occurs  at  make  and  none 
at  break.  Reverse  the  commutator  to  get  a  descending  current, 
make  and  break,  observing  again  a  contraction  at  make  and  none  at 
break.     This  represents  the  effect  of  a  weak  current.     Sometimes 


248 


PRACTICAL  PHYSIOLOGY. 


[XLIX. 


the  current  so  obtained  is  not  weak  enough.  The  simple  rheochord 
should  then  be  used  (p.  163). 

(c.)  Pull  the  sUder  farther  away  and  remove  one  or  more  plugs 
until  contraction  is  obtained  at  make  and  break,  both  with  an 
ascending  and  descending  ciirrent.  This  represents  the  effect  of  a 
medmrn  current. 

{d.)  Use  six  small  Grove's  cells,  take  out  all  the  plugs  from  tlie 
rheochord,  and  with  the  current  ascending,  contraction  occurs  at 
])reak  only  ;  while  with  a  descending  current,  contraction  occurs 
only  at  make.  This  represents  the  effect  of  a  strong  current. 
Tabulate  the  results  in  each  case. 

For  this  experiment  very  fresh  and  strong  frogs  are  necessary,  and  several 
preparations  may  be  required  to  work  out  all  the  details  of  the  law.  Instead 
of  reversing  the  commutator  after  testing  the  efifect  of  an  alteration  of  the 
direction  of  the  current,  the  student  may  use  one  preparation  to  test  at 
intervals  the  efifect  of  weak,  medium,  and  strong  currents  when  the  current 
is  ascending,  and  a  second  preparation  to  test  the  results  with  currents  of 
varying  intensity  when  the  current  is  descending.  The  results  may  be 
tabulated  as  follows  :  R  =  rest :  C  =  contraction  : — 


ASCBNDINQ. 

Descending. 

Strehgth  or  Cd&rkht. 

On  Making. 

On  Breaking. 

On  Making. 

On  Breaking. 

Weak,     . 

0 

R 

C 

R 

Medium,          • 

0 

0 

^ 

C 

Strong,    . 

R 

0 

c 

R 

2.  Electrotonic  Variation  of  the  Electro-motivity. 

(a.)  Arrange  a  long  nerve  on  N.P.  electrodes,  as  for  determining  its  demar- 
cation-current. Place  the  free  end  of  the  nerve  on  a  pair  of  N.P.  electrodes 
— tlie  polarising  current— arranged  as  in  Lesson  XLVIII.,  so  that  the  current 
can  be  made  ascending  or  descending. 

(6.)  Take  the  deflection  of  the  galvanometer  needle  or  demarcation -current 
when  the  jwlarising  current  is  shut  oflf.  Throw  in  a  descending  polarising 
current,  and  observe  that  the  spot  of  light  travels  towards  zero.  Reverse  the 
commutator  and  throw  in  an  ascending  current,  the  s]>ot  of  light  shows  a 
greater  positive  variation  than  before.  From  this  we  conclude  that  kathe- 
lectrotonus  dimi7iishcs  the  eledro-motivity ,  xrhile  anehctrotonus  increases  it. 
In  the  extra-polar  kathodic  region  an  electrotonic  current  appears  when  the 
polarising  current  is  closed.  It  has  the  same  direction  as  the  polarising 
current.  In  the  anodic  region  the  direction  is  also  that  of  the  polarising 
current ;  but  the  electrotonic  current  is  stronger  than  the  kathodic  current 
If  a  demarcation-current  exists  already,  the  electrotonic  currents  are  super- 
posed on  it. 


XLIX.] 


pflOger's  law  of  contraction. 


249 


3.  Ritter's  Tetanus. 

(a.)  Connect  three  Daniell's  cells  with  N.P.  electrodes,  short-circuiting 
with  a  Du  Bois  key.  Make  a  nerve-muscle  preparation,  and  ajtply  the 
electrodes  to  the  nerve  so  that  the  -f-  pole  is  next  the  inusclo,  i.e.,  the  current 
is  ascending  in  the  nerve.  Allow  the  current  to  circulate  in  the  nerve  for 
some  time  (usually  about  five  minutes  is  sufficient),  no  contraction  takes 
place.     Short-circuit,  and  the  muscle  becomes  tetanic. 

(h.)  Divide  the  nerve  between  the  electrodes,  and  the  tetanus  does  not 
cease  ;  but  on  dividing  it  between  the  +  pole  and  the  muscle,  the  tetanus 
ceases.  Therefore  the  tetanus  is  due  to  some  condition  at  the  positive  pole, 
i.e.,  the  stimulation  proceeds  from  the  positive  pole  at  break. 

4.  Kathodic  Stimulus  is  the  more  powerful. 

(a.)  Let  the  M.  and  B.  shocks  be  made  approximately  equal  by  the  arrange- 
ment shown  in  fig.  174.     In  the  secondary  circuit  place  a  Pohl's  commutator 


FlO.  174.— Scheme  to  show  that  Kathodic  Stinuilation  is  the  more  powerfuL    K.  Key ; 
R.  Commutator  ;  F.  Frog's  leg  ;  c.  One  electrode. 


with  cross-bars  (R).     Place  one  electrode  (c-)  under  the  sciatic  nerve,  and  Uie 
ocher  on  another  part  of  the  body. 

{b.)  Suppose  c  to  be  the  cathode,  select  a  strength  of  shock,  i.e.,  distance 
of  secondary  from  ])rimary  coil,  so  that  there  is  response  on  b-reaking  the 
j'limary  current.  Reverse  the  commutator  so  that  c  becomes  the  anode. 
There  is  no  muscular  response  at  break,  but  it  occurs  at  make,  as  c  is  then 
the  cathode. 


5.  Rheochord  of  Du  Bois-Reymond  is  used  to  vary  the  amount  of  a 
cmisiant  current  applied  to  a  muscle  or  nerve  (fig.  175).  It  consists  of  a  long 
box,  with  German-silver  wire —of  varying  length,  and  whose  resistance  is 
accurately  graduated — stretched  upon  it.  At  one  end  are  a  series  of  brass 
blocks  disconnected  with  each  other  above,  but  connected  below  by  a  German- 
silver  wire  passing  round  a  pin.  These  blocks,  however,  may  be  connected 
directly  by  brass  plugs,  S,  S.2  .  .  .  Sr,.  From  the  blocks  i  and  2  two  ])]atinum 
wires  pass  from  A  to  the  opposite  end  of  the  box  (Y),  where  they  are  insu- 
lated. Between  the  wires  is  a  "slider"  (L),  consisting  of  two  brass  cups 
containing  mercury,  which  slide  along  the  wires. 


250 


PRACTICAL   PHYSIOLOGY. 


[L 


In  usiiig  the  instrument,  connect  a  Daniell's  cell  to  the  binding  screws  at 
A  and  B,  and  to  the  same  screws  attach  the  wires  of  the  electrodes  over 

which  the  nerve  (c  d)  of  the  muscle 
(F)  is  laid.  We  have  two  circuits 
{a  c  d  h  and  a  A  B  fe) ;  the  wires  of 
the  rheochord  are  introduced  into  the 
latter. 

Push  up  the  slider  with  its  cups  (L) 
until  it  touches  the  two  brass  plates 
I  and  2,  and  insert  all  the  plugs 
(8,-85)  in  their  places,  thus  making 
the  several  blocks  of  brass  practically 
one  block.  In  this  position,  the  zero 
of  the  instrument,  the  resistance  offered 
by  the  rheochord  circuit  is  so  small  as 
compared  with  that  including  the  nerve, 
that  practically  all  the  electricity  passes 
through  the  former  and  none  through 
the  latter. 

Move  the  slider  away  from  A,  when 
a  resistance  is  thrown  into  the  rheo- 
chord circuit,  according  to  the  length 
of  the  platinum  wires  thus  introduced 
into  it,  and  so  a  certain  fraction  of  the 
current  is  sent  through  the  electrode 
circuit.  If  the  plug  8,  be  taken  out, 
more  resistance  is  introduced,  that  due 
to  the  German-silver  wire  (I  //),  and, 
therefore,  a  certain  amount  of  the 
current  is  made  to  pass  through  the 
electrode  circuit.  By  taking  out  plug 
after  plug  more  and  more  resistance  is 
thrown  into  the  rheochord  circuit.  The 
plugs  are  numbered,  and  the  diameter 
and  length  of  the  German-silver  wires 
are  so  selected  in  making  the  instru- 
ment, that  the  resistances  represented 
plugs  when  removed  are  all  multiples  of  the  resistance 
the  slider  moves.  Proceed  taking  out  plug 
The  result,  and  explanation  thereof,  are 


Fig. 


175. — R.heochord  of  Du 
Bois-Reymond. 


by   the   several 

in  the  platinum  wires  on  which 
after  plug,  and  note  the  result. 
referred  to  in  Lesson  XLIX.  1. 


LESSON  L. 

VELOCITY  OF  NERVE-IMPULSE  IN  FROG,  MAN- 
DOUBLE  CONDUCTION  IN  NERVE— KUHNE'S 
GRACILIS  EXPERIMENT,  &c. 


1.  Velocity  of  Nerve-Energy  in  a  Frog's  Motor  Nerve. 

The  rate  of  propagation  of  a  nerve-impulse  or  excitatory  change 
may  be  estimated  by    either    the  pendulum  or   spring-myograph. 


L.] 


VELOCITY   OF  NERVE-IMPULSE. 


251 


With  slight  modifications  the  two  processes  are  identical,  only  in 
using  the  spring-myograph  it  is  necessary  to  use  such  a  coiled  spring 
as  will  canse  the  glass  plate  to  move  with  sufficient  rapidity  to  give 
an  interval  long  enough  for  the  estimation  of  the  latent  period.  It 
may  be  done  also  on  a  revolving  drum  provided  the  drum  moves 
with  sufficient  rapidity. 

(a.)  Use  the  spring-myograph  and  arrange  the  experiment 
according  to  the  scheme  (fig.  176),  i.e.,  an  induction  coil  for  single 
shocks  with  the  trigger-key  of  the  myograph  (i,  2)  in  the  pidmary 
circuit;  in  the  secondary  circuit  (which  should  be  sliort-circuited, 
not  represented  in  the  diagram)  place  a  Pohl's  commutator  icithout 
cross-bars  (C).  Two  pairs  of  wires  from  the  commutator  pass  to 
two  pairs  of  electrodes  («,  h),  arranged  on  a  bar  in  the  moist 
chamber,     Measui'e  the  distance  between  the  electrodes. 


FlQ.  176. 


-Scheme  for  Estimating  the  Velocity  of  Nerve-Energy. 


{h,)  Make  a  nerve-muscle  preparation  with  a  long  nerve  (N), 
clamp  the  femur  (/),  attach  the  tendon  {m)  to  a  writing-lever,  and 
lay  the  nerve  over  the  electrodes,  the  distance  between  them  being 
known.  It  is  well  to  cool  the  nerve  by  iced  normal  saline,  as  the 
velocity  of  the  impulse  is  thereby  much  diminished. 

(c.)  Arrange  the  glass  plate  covered  with  smoked  paper,  adjust 
the  lever  to  mark  on  the  glass,  close  the  trigger-key  in  the  primary 
circuit,  and  unshort-circuit  the  secondary.  Turn  the  bridge  of  the 
commutator  so  that  the  stimulus  will  be  sent  through  the  electrodes 
next  the  muscle  (a).  Press  the  thumb  plate,  the  glass  plate  shoots 
across.  The  tooth  (3)  breaks  the  primary  circuit,  and  a  curve  is 
inscribed  on  the  plate. 

{(i.)  Short-circuit  again,  replace  the  glass  ])late,  close  the  trigger- 
key,  reverse   the  commutator.     This  time   the  stimulus  will  pasa 


25?  PRACTICAL  PHYSIOLOGY.  [L. 

through  the  electrodes  away  from  the  muscle  (h).  Unshort-circiiit 
the  secondary  circuit,  and  shoot  the  glass  plate,  when  another 
curve  will  be  inscribed,  this  time  a  Uff/e  laftv  than  the  first  one. 

{e.)  Replace  the  glass  plate,  close  the  trigger-key,  short-circuit 
the  secondary  circuit,  and  shoot  the  plate.     This  mak*es  the  abscissa. 

(/.)  Replace  the  glass  plate,  close  the  trigger-key,  and  bring  the 
tooth  of  the  glass  plate  (3)  just  to  touch  the  trigger-key ;  raise  the 
writing-lever  to  make  a  vertical  mark.  This  indicates  the  moment 
wlien  the  stimuhis  was  thrown  into  both  points  of  the  nerve. 

(f/.)  Remove  the  moist  chamber,  push  up  the  glass  plate,  close 
the  trigger-key,  and  arrange  a  tuning-fork  vibrating  250  D.V.  per 
second  to  write  under  the  abscissa.  Shoot  the  plate  again  and  the 
time-curve  Avill  be  obtained.  Fix  the  tracing,  draw  ordinates  from 
the  beginning  of  the  curves  obtained  by  the  stimulation  of  a  and  h 
respectively,  measure  the  time  between  them  from  the  time-curve 
(this  gives  the  time  the  impulse  took  to  travel  from  h  to  a),  and 
calculate  the  velocity  from  the  data  obtained. 

Example. — Suppose  the  length  of  nerve  to  be  4  cm.,  and  the  time 
required  for  the  impulse  to  travel  from  h  to  a  to  be  yi^  sec.  Then 
we  have  4  :  100  :  730"  •  Fo"j  ^^  3°  metres  (about  98  feet)  per 
second,  as  the  velocity  of  nerve-energy  along  a  nerve. 

2.  Repeat  the  observation  Avith  the  pendulum-myograph. 
Practically  the  same  arrangements  are  necessary. 

If  it  be  desired  to  test  the  effect  of  heat  or  cold  on  the  rapidity 
of  propagation,  the  nerve  must  be  laid  on  ebonite  electrodes,  made 
in  the  form  of  a  chamber,  and  covered  with  a  lacquered  copper 
plate  on  Avhich  the  nerve  rests.  Through  the  cliamber  water  at 
different  temperatures  can  be  passed,  and  the  effect  on  the  rate  of 
propagation  observed. 

3.  Velocity  of  Motor  Nerve-Impulse  in  Man. 

{a.)  Use  a  pendulum-myograph.  Connect  two  Daniell's  cells 
with  the  primary  circuit  of  an  induction  coil  and  interpose  in  the 
circuit  the  trigger-key  of  the  myograph,  which  the  pendulum  opens 
in  swinging  past.  Place  a  short-circuiting  key  in  the  secondary 
circuit,  and  to  the  short-circuiting  key  attach  a  pair  of  rheophores 
moistened  with  strong  solution  of  salt. 

(6.)  Arrange  Marey's  ^^ pinae  myographique  "  (fig.  1 5 1)  to  compress 
the  adductor  muscles  of  the  thumb  when  the  latter  is  in  the 
abducted  position.  Connect  the  "  pince "  by  means  of  an  india- 
rubber  tube  with  a  Marey's  tambour  (fig.  150)  arranged  to  record 
its  movements  on  glazed  paper  fixed  to  the  plate  of  the  pendulum- 
myograph. 

(c.)  The  nerve  supplying  the  adductor  muscles  of  the  thumb 


L.]  VELOCITY   OF    NERVE-IMPULSE.  253 

must  be  stimulated  first  near  tlie  ball  of  tlie  thumb,  and  secondly 
at  the  bend  of  tlie  elbow.  Contraction  takes  place  sooner  from  the 
former  than  from  the  latter  position.  Suppose  the  right  thumb  to 
be  used,  apply  one  rheophore  to  the  right  side  of  the  chest,  and 
the  other  to  just  over  the  ball  of  the  thumb.  Allow  the  pendulum 
to  swing.  Take  a  tracing.  Replace  pendidum,  short-circuit  the 
secondary  circuit,  close  the  trigger-key. 

{(l.)  Open  the  secondary  circuit.  Apply  the  arm  rheophore  to 
the  median  nerve  at  the  bend  of  the  elbow  and  record  another 
contraction. 

((?.)  Record  a  base-line  and  mark  the  point  of  stimulation  on  the 
myograph  plate.     Make  a  time-tracing  under  the  two  muscle  curves. 

(/'.)  Measure  the  distance  between  (i.)  the  two  arm  electrodes ; 
(ii.)  the  beginning  of  the  two  curves;  (iii.)  note  the  time- value  of 
(ii.)  as  indicated  by  the  time  curve ;  and  from  these  data  calculate 
the  time  the  nervous  impulse  took  to  travel  from  the  elbow  to 
the  nerve  supplying  the  muscles  of  the  ball  of  the  thumb. 


ADDITIONAL  EXERCISES. 

4.  Double  Conduction  in  Nerve— Kiihne's  Experiment  on  the  Gracilis.— 

The  gracilis  is  divided  into  a  larger  and  smaller  portion  (L)  by  a  tendinous 
Inscription  (K)  running  across  it  (fig.  177).  The  nerve  (N)  enters  at  the  hilum 
in  the  larger  half,  and  bifurcates,  giving  a  branch  {!:)  to  the  smaller  portion, 
and  another  to  the  larger  portion  of  the  muscle,  but  neither  branch  reaches 
quite  to  the  end  of  either  half  of  the  muscle. 

{a.)  Remove  the  gracilis  (rectus  internus  major  and»  minor) 
(Ecker).  The  method  of  removing  semi-membranosus  and  gracilis 
together  has  already  been  described  (Lesson 
XXIX.  5).  Place  a  pithed  and  skinned  frog  on 
its  back.  In  order  to  see  the  outline  of  the  thigh 
muscles  better,  moisten  them  with  blood.  The 
sartorius  by  its  inner  margin  lies  in  relation  with 
the  gracilis  near  its  lower  attachment,  the  gracilis 
itself  lying  on  the  ventral  surface  of  the  inner 
part  of  the  thigh,  having  its  origin  at  the  sym- 
physis, and  its  insertion  at  the  tibia.  The  small 
part — minor — is  attached  to  the  skin  and  is 
usually  torn   through  when  the  skin  is  removed.    Fro.  177.— KUhne's 

-,1      .,  "^     ,,  .  ^.,    .      .  J.      i.       -ii    xi  •  Experiment     on 

JJy  its  other  margin  it  is  in  contact  with  the  semi-       the  Gracilis, 
membranosus.    The  muscle  is  detached  from  below 
upwards.     Its  tendinous  inscription  or  intersection  is  readily  visible 
on  a  black  surface. 


254  PRACTICAL   PHYSIOLOGY.  [LL 

{b.)  Cut  it  as  in  fig.  177,  avoiding  injury  to  the  nerves,  so  that  only  the 
nerve  twig  {k)  connects  the  larger  and  smaller  halves,  and  in  one  tongue  (Z) 
terminates  a  nerve.  After  excision  lay  it  on  a  glass  plate  with  a  black  back- 
ground, else  one  does  not  see  clearly  the  inscription  and  the  course  of  the 
nerves. 

(f.)  Stimulate  the  tongue  (Z)  with  fine  electrodes  about  i  mm.  apart,  and 
contraction  occurs  in  both  L  and  K.  This,  according  to  Kiihne,  is  due  to 
centripetal  conduction  in  a  motor  nerve.  This  experiment  is  adduced  by  him 
as  the  best  proof  of  double  conduction  in  nerve  fibres.  Mays  has  shown  that 
the  nerve  fibre  divides  and  supplies  both  halves  of  the  muscle. 

{(L)  If  the  muscle  be  exposed  in  a  curarised  frog,  on  stimulating 
either  half  of  the  muscle  with  repeated  shocks,  only  that  half 
responds,  as  the  inscription  blocks  the  passage  of  the  muscle-wave. 

{e.)  If  an  uncurarised  muscle  is  used,  stimulation  of  the  muscle 
near  its  ends  causes  response  only  in  its  own  half.  Why  ?  Because 
there  are  no  nerves  there;  but  stimulation  near  the  inscription 
causes  response  in  both  halves.  Why  1  Because  they  are  excited 
through  their  nerves,  as  shown  definitely  by  (c). 

5.  Action  of  a  Constant  Current  — In  muscle  and  nerve,  stimulation  occurs 
only  at  the  kathode  when  the  current  is  made  (closed),  and  at  the  anode  when  it 
is  broken  {opened)— (V,  Bezold).  This  is  most  readily  seen  in  fatigued 
muscles. 

(A.)  Engelmann's  Experiment. — {a.)  Suspend  vertically  a  curarised  sar- 
torius  of  a  frog,  and  pass  a  constant  current  through  its  upper  extremity. 
On  making  the  current,  the  muscle  moves  towards  the  side  of  the  kathode, 
because  contraction  occurs  at  the  kathode  on  making.  At  break,  it  inclines 
to  the  anode. 

{b.)  Slit  up  the  muscle  longitudinally,  so  that  it  looks  like  a  pair  of 
trousers,  and  keep  the  two  legs,  as  it  were,  asunder  by  an  insulating  medium  ; 
at  make,  the  kathodic  half  alone  contracts  ;  at  break,  the  anodic  half. 

(B, )  Another  Method. — Dissect  out  the  sartorius  of  a  curarised  frog,  but 
remove  it  with  its  bony  attachments,  clamp  it  at  its  centre,  and  arrange  it 
either  vertically  as  in  fig.  191,  attaching  its  ends  to  two  recording  levers 
placed  one  above  it  and  the  other  below  it,  or  fix  it  on  a  double  crank-myo- 
graph.  Pass  thin  wires  from  the  battery  through  the  two  ends  of  the  muscle  ; 
on  making  the  current,  the  lever  attached  to  the  kathode  rises  before  the 
other,  i.e.,  where  the  current  leaves  the  muscle.  On  breaking  the  current, 
the  anodic  lever  rises  first,  showing  that  the  anodic  half  contracts  before  the 
kathodic  halt 


LESSON  LI. 

OTHER  CONDITIONS  AFFECTING  THE  EXCITA- 
BILITY OF  NERVE  —  CHEMICAL,  TEMPERA- 
TURE, &c. 

1.  Unequal  Excitability  of  Diflferent  Portions  of  a  Motor 
Nerve. — Apparatus. — Cell,  two  keys,  wires,  commutator,  induction 
coil,  either  for  single  or  faradic  shocks,  two  pairs  of  electrodes. 


LI.] 


EXCITABILITY   OF   NERVE. 


255 


(a.)  Arrange  the  apparatus  as  in  fig.  178.  Dissect  out  the  whole 
length  of  the  sciatic  nerve  w.ith  the  leg  attached.  Lay  the  nerve 
on  two  pairs  of  electrodes,  A  and  B,  one  near  the  muscle  and  the 
other  away  from  it,  and  as  far  apart  as  possible.  Two  pairs  of 
wires  thrust  tlirough  a  cork  will  do  quite  well. 

(6.)  Stimulate  at  A  with  a  current  that  gives  a  minimal  contrac- 
tion. Reverse  the  commutator.  Stimulate  at  B,  a  stronger 
contraction  is  obtained,  because  the  excitability  of  a  nerve  is 
greater  farther  from  a  muscle  or  nearer  the  centre.  Instead  of 
using  single  shocks,  repeated  shocks  by  means  of  Neef's  hammer 
may  be  used. 


Fig.  178. — Scheme  for  the  Unequal  Excitability  of  a  Nerre. 

2.  Effect  of  Temperature  on  Excitability  of  a  Nerve. 

(a.)  Fix  a  nerve-muscle  preparation  on  a  crank-myograph,  so  as 
to  record  on  a  revolving  cylinder  provided  with  an  automatic  break- 
key  placed  in  the  primary  circuit  of  an  induction  coil,  and  so 
arranged  as  to  give  only  feeble  break  sliocks. 

{b.)  Bring  a  test-tube  filled  with  water  at  80-90°  C.  near  the 
nerve,  where  the  electrodes  lie  on  it.  Soon  the  contraction 
increases  and  may  become  maximal. 

(c.)  Remove  the  source  of  heat  and  the  contractions  become  lessy 
i.e.,  the  excitability  falls. 

(d.)  Similar  results  may  be  obtained  by  the  direct  appHcation 
of  warm  normal  saline  to  a  nerve. 

(For  other  kinds  of  nerve  fibres  see  "  Effects  of  stimulation  and 
of  changes  in  temperature  upon  irritabihty  and  conductivity  of 
nerve  fibres,"  by  llowell  and  others,  Journal  of  Physiology^  xvi. 
p.  298.) 

3.  Salt  Increases  the  Excitability  of  a  Nerve. 

(a.)  Arrange  a  nerve-muscle  preparation  as  in  2,  and  determine 


256  PRACTICAL  PHYSIOLOGY.  [U. 

the  distance  of  the  secondary  from  the  primary  coil  to  obtain  a 
minimal  stimulus,  i.e.,  response.  Apply  a  drop  of  saturated  solution 
of  common  salt  to  the  nerve  between  tlie  electrodes  and  the  muscle. 
Almost  at  once  the  excitability  of  the  nerve  is  increased,  as  shown 
by  the  height  of  the  contraction,  so  that  the  excitabihty  increases 
at  once. 

(/>.)  After  several  minutes  the  muscles  begin  to  twitch,  the  salt 
acting  as  a  chemical  stimulus.  It  is  thus  evident  that  the  excita- 
bility is  early  increased,  but  before  muscular  response  to  chemical 
stimulation  is  elicited  a  considerable  time  elapses. 

4.  Effect  of  Section  on  the  Excitability  of  a  Nerve. 

{a.)  Arrange  a  coil  for  single  shocks,  expose  the  sciatic  nerve 
in  a  pithed  frog,  and  under  it,  near  its  central  end,  place  insulated 
electrodes,  using  single  break  shocks.  Ascertain  the  distance  of 
the  secondary  from  the  primary  coil  at  which  the  break  shock  is 
just  too  weak  to  cause  the  muscles  to  respond  (sub-minimal). 

(A.)  With  a  sharp  pair  of  scissors  divide  the  sciatic  nerve  on  the 
central  side  of  the  electrodes.  The  stimulus  (previously  sub-minimal) 
now  causes  a  stro^ig  contraction. 

{c.)  Ascertain  the  distance  (perhaps  several  cm.)  to  which  the 
secondary  coil  must  be  pushed  away  from  the  primary  in  order  to 
obtain  again  a  sub-minimal  stimulus.  The  condition  of  increased 
excitability  lasts  for  some  time. 

5.  Excitability  of  Flexors  and  Extensors  (Rollett). 

Arrange  a  coil  for  repeated  shocks.  Expose  either  the  sciatic 
nerve  or  the  sciatic  plexus  in  a  pithed  frog.  Select  a  weak 
current,  and  flexion  of  the  leg  muscles  is  obtained ;  on  pushing  up 
the  secondary  coil,  the  extensors  prevail 

6.  Functions  of  Different  Motor  Nerves  (Sciatic  Plexus). 

Strip  off  the  skin  from  the  hind-legs  of  a  pithed  frog.  Open 
the  abdomen  and  expose  the  sciatic  plexus,  the  frog  being  placed 
on  its  back.  Stimulate  with  faradic  electricity — selecting  a 
strength  of  current  just  adequate  to  yield  a  muscular  response — 
each  of  the  three  cords  forming  the  sciatic  plexus.  The  upper  cord 
supplies  muscles  acting  chiefly  on  the  hip-joint,  the  lowest  acts 
chiefly  on  the  muscles  moving  the  ankle  and  toes,  and  the  middle 
one  on  the  muscles  acting  on  the  knee-joint. 

7.  Conductivity  v.  Excitability  (Grlinhagen's  Experiment). 
(a.)  Pass  the  nerve  of  a  frog's  leg  through  a  glass  tube  (fig.  179), 

sealing  the  ends  with  clay,  but  not  compressing  the  nerve.  The 
tube  is  supplied  with  an  inlet  and  outlet,  to  which  elastic  tubes  can 


LI.] 


EXCITABILHT    OF   NERVE. 


257 


IM. 


be  attached  and  through  which  vapours  or  gases  can  be  passed,  and 
also  with  electrodes  so  that  the  nerve  can  be  stimulated  within  or 
outside  the  tube.     Use  a  Pohl's  commutator  for  this  purpose. 

{h.)  Pass  CO^  from  a  Kipp's  apparatus  through  the  tube;  on 
stimulating  the  nerve  at  A 
with  repeated  shocks,  there  is 
no  response,  but  on  stimulating 
at  B  there  is.  Find  a  strength 
of  stimulus  which  just  excites 
the  nerve  at  A  and  B.  On 
passing  COg  A  no  longer  re- 
sponds to  this  stimulus,  but 
rerjuires  a  stronger  stimulus,  or 
it  may  not  respond  at  all.  It 
would  s^fem  that  the  excitatory 
change  set  up  at  B  is  propagated 
through  A,  although  its  excita- 
bility is  very  feeble  or  nil.  It 
thus  seems  to  conduct,  even 
though  it  is  inexcitable. 

{('.)  On  passing  the  vapour  of 
alcohol  the  conductivity  appears  to  vanish  before  the  excitability. 
It  is  better  to  suck  the  vapour  through  by  means  of  an}''  form  of 
exhaust  pump.  The  results,  however,  may  be  capable  of  a  dififerent 
interpretation.  (Gad,  Dm  Bou-ReymoncVs  ArcJiir,  1888,  p.  395, 
and  1889,  p.  350;  Piotrowski,  "  Trennung  d.  Peizbark.  v. 
Leitungsfah.  d.  Nerven,"  iUd.^   1893,  p.   205.) 

{d.)  Cold. — Apply  cold  to  a  nerve  as  in  8,  i.e.,  lay  the  nerve  over 
a  glass  tube  through  which  cold  water  is  conducted.  Cold,  like 
CO.^,  abolishes  or  diminishes  the  excitability,  but  not  the  con- 
ductivity. 

The  action  of  other  substances,  such  as  chloroform,  ether,  and 
CO,  have  been  investigated. 


Fig.  179 


Gninhagen's  Experiment  on 
Conductivity  v.  Excitability. 


ADDITIONAL  EXERCESES. 


8.  Influence  of  Localised  Cold  upon  Excitabili  y  (Grotch). 

A.  Upon  Nerve. 

The  influence  of  changes  in  temperature  upon  excitability  can  be  investi- 
gated by  arranging  in  the  moist  chamber  a  glass  tube  j)laced  at  right  angles 
to  the  nerve  of  a  nerve-muscle  preparation,  and  situated  so  that  a  small 
portion  of  the  nerve  shall  lie  athwart  the  tube.  Through  the  tube  water  at 
temperatures  varied  at  will  from  10°  to  30°  C.  is  allowed  to  flow. 

The  alteration  in  temperature  causes  a  marked  alteration  in  the  electrical 


258  PRACTICAL  PHYSIOLOGY.  [LL 

resistance  of  the  tissue,  this  being  lowered  by  warmth  and  raised  by  cold  ;  in 
ordtT  to  get  rid  of  this  purely  physical  change,  it  is  essential  that  a  large 
resistance  should  be  introduced  into  the  exciting  circuit.  This  is  most 
simply  done  by  using  non-i>olarisable  electrodes  with  threads  attached  to  the 
ends  of  the  electrodes  kept  moist  by  normal  saline  solution.  The  threads  are 
now  arranged  so  as  to  touch  the  nerve  where  it  lies  on  the  tube,  one  thread 
being  placed  so  that  the  contact  shall  be  on  the  edge  of  the  cooling  tube 
nearest  the  muscle.  The  simplest  method  of  exciting  the  nerve  is  by  means 
of  a  weak  galvanic  current.  For  this  purpose  the  rheochord  is  used  and  a 
weak  current  employed  of  such  direction  that  it  shall  descend  the  nerve  and 
thus  excite  this  at  the  cathodic  contact  on  the  distal  edge  of  the  glass  tube. 

In  order  to  ensure  that  the  galvanic  current  is  always  of  the  same  duration, 
it  is  desirable  to  close  the  current  by  an  automatic  arrangement,  either  a 
revolving  drum  carrying  a  striker  which  shall  at  each  revolution  strike  a 
stretched  wire,  or  a  metronome  ;  but  the  influence  of  the  temperature  alteration 
may  be  obtained-  without  this  arrangement,  the  closure  being  effected  by  a 
Pohl's  reverser  without  cross  lines  as  a  double  make  mercurial  key  worked  by 
the  hand. 

The  nerve-muscle  preparation  having  been  made  and  the  muscle  attached 
to  an  appropriate  lever,  so  as  to  record  its  contraction  uj)on  a  very  slowly 
moving  surface,  an  intensity  of  current  is  ascertained,  which,  with  the  nerve 
at  the  normal  temperature  of  the  room,  is  only  just  adequate  to  evoke  a  very 
weak  minimal  muscular  response  whenever  the  circuit  is  closed. 

The  temperature  of  the  nerve  is  now  raised  by  allowing  water  at  30°  C.  to 
pass  through  the  tube,  when  the  response  will  disappear  ;  the  temperature  is 
now  lowered  by  allowing  water  at  10^  C.  or  less  to  flow — the  response  is  now 
very  marked.  Localised  cold  thus  increases  the  excitability  of  nerve  to  this 
form  of  stimulus.  Similar  eflects  can  be  obtained  with  the  condenser  dis 
charge,  with  mechanical  and  with  chemical  stimuli.  If  the  induction 
current  is  used  instead  of  the  galvanic  current,  a  reverse  effect  is  obtained, 
the  nerve-muscle  preparation  responding  better  when  the  excited  nerve  is  at 
30''  C.  ;  and  this  favourable  influence  of  warmth  persists  even  when  a  very 
large  external  resistance  is  introduced  into  the  circuit. 

B.  Upon  Muscle. 

The  sartorius  muscle  of  the  frog  is  used  for  this  experiment,  the  threads  of 
the  exciting  electrodes  being  placed  upon  the  broad  "nerveless"  pelvic  end 
of  the  muscle  under  which  the  tube  of  the  cooling  arrangement  is  lixed.  It 
is  then  found  that  the  muscle  responds  better  when  cooled  to  every  form  of 
stimulus  applied  to  the  cooled  region,  including  the  induction  current.  If 
the  electrodes  be  shifted  to  the  "nerved"  portion  of  muscle,  the  response, 
being  indirect,  is  disfavoured  by  cold  when  the  induction  current  is  used.— 
(Communicated  by  Fro/essor  Gotch.)    See  also  Journal  of  Fhys,^  XII. 


LII.]  THE   frog's  heart.  259 


PHYSIOLOGY  OF  THE  CIRCULATION. 


LESSON  LII. 

THE  FROG'S  HEART— BEATING  OP  THE  HEART— 
EFB^BCT  OF  HEAT  AND  COLD— SECTION  OF 
THE  HEART. 

1.  Heart  of  the  Frog  and  how  to  Expose  it. 

(a.)  Pith  a  frog,  and  lay  it  on  its  back  and  pin  ont  its  legs  on 
a  frog-plate.  Make  a  median  incision  through  the  skin  over  the 
sternuin,  continue  the  incision  upwards  and  downwards,  and  from 
the  middle  of  the  sternum  make  transverse  incisions. 

(b.)  Reflect  the  four  flaps  of  skin,  raise  the  lower  end  of  the 
episternum  with  a  pair  of  forceps,  and  cut  through  the  sternal  carti- 
lage just  above  its  lower  end,  to  avoid  wounding  the  epigastric 
vein.  With  a  strong  pair  of  scissors  cut  along  the  margins  of  the 
sternum,  and  divide  it  above.  Do  not  injure  the  heart,  wliich  is 
exposed  still  beating  within  its  pericardium. 

(c.)  With  a  fine  pair  of  forceps  carefully  lift  up  the  thin  trans- 
parent pericardium,  and  cut  it  open,  thus  exposing  the  heart. 

2.  General  Arrangement  of  the  Frog's  Heart. 

(a.)  Observe  its  shape,  noting  the  two  auricles  above  (fig.  i8o, 
A^,  As),  and  the  conical  apex  of  the  single  ventricle  below  (?;),  the 
auricles  being  mapped  ofi'  from  the  ventricle  by  a  groove  which 
runs  obUquely  across  its  anterior  aspect.  The  ventricle  is  con- 
tinuous anteriorly  with  the  bulbus  aortae  (B),  which  projects  in 
front  of  the  right  auricle,  and  divides  into  two  aortae — right  and 
left,  the  left  being  the  larger. 

(b.)  Tilt  up  the  ventricle  and  observe  the  sinus  venosus  (fig. 
1 8 1,  s.v.)  continuous  with  the  right  auricle,  and  formed  by  the 
junction  of  the  large  inferior  vena  cava  {e.i.)  and  the  two  (smaller) 
superior  vense  cavae  {c.s.s,  c.s.d). 

3.  Note  the  sequence  of  contraction  of  the  several  parts,  viz., 
sinus  venosus,  auricles,  ventricle,  and  bulbus  arteriosus. 

Tliis  sequence  of  events  is  difiicult  to  note,  but  what  can  be 
easily  observed  is  the  relative  condition  of  vascularity  of  the 
ventricle.  The  frog's  ventricle  has  no  blood-vessels  supplying  its 
muscular  walls.  Note  that  during  systole  of  the  ventricle,  i.«., 
during  its  contraction,  it  becomes  pale,  and  immediately  thereafter, 


26o 


PRACTICAL  PHYSIOLOGY. 


[lil 


during  its  diastole,  it  is  distended  with  blood  and  has  a  red  appear- 
ance, the  blood  flowing  into  it  being  propelled  by  the  contracting 
auricles.     Notice  also  how  the  position  of  the  auriculo-ventricular 
groove  moves  upwards  and  downwards  during  each  cardiac  cycle. 
Kote  the  normal  rhythm,  i.e.,  the  number  of  beats  per  minute. 

4.  Effect  of  Temperature  (Heart  in  situ). 

(a.)  By  means  of  a  pipette  allow  a  few  drops  of  normal  saline  at 
2o°-2  5°  C.  to  bathe  the  heart,  and  note  how  rapidly  the  number 
of  beats,  i.e.,  rhythm,  is  increased,  and  how  each  individual  beat 
is  quicker. 


ej&d. 


FIO.  i8o.  —  Frog's  Heart 
from  the  front  v.  Single 
ventricle;  Ad,  As.  Right 
and  left  auricles ;  B. 
Bulbus  arteriosus ;  i. 
Carotid ;  2.  Aorta ;  3. 
Pulrao  -  cutaneous  arte- 
ries ;  C.  Carotid  gland. 


SlQ.  181.— Heart  of  Frog  from  Behind. 
$.v.  Sinus  venosus  opened;  c.i.  In- 
ferior, c.s.d,  c.8.8.  Right  and  left 
superior  venae  cavae  ;  v.p.  Pulmonary 
vein  ;  A.d,  and  A.s.  Right  and  left 
auricles ;  A.p.  Communication  be- 
tween the  right  and  left  auricle. 


{h.)  Then  apply  normal  saline  at  10°  C.  or  5°  C,  and  note  the 
opposite  effect  on  the  rate  or  rhythm,  together  with  the  slower 
contraction  of  each  individual  beat. 

5.  An  Excised  Heart  Beats. 

{a.)  With  a  seeker  tilt  up  the  apex  of  the  ventricle,  and  observe 
that  a  thin  thread  of  connective  tissue,  called  the  "  frsenum," 
containing  a  small  vein,  passes  from  the  pericardium  to  the  posterior 
aspect  of  the  ventricle.  Tie  a  fine  silk  thread  round  the  frsenum 
and  divide  it  dorsal  to  the  ligature.  Count  the  number  of  beats 
per  minute.  By  means  of  the  silk  thread  raise  the  heart  as  a 
whole,  and  with  a  sharp  pair  of  scissors  cut  out  the  heart  by  divid- 
ing the  inferior  vena  cava,  the  two  superior  venae  cavae,  and  the 
two  aortae.  Place  the  excised  heart  in  a  watch-glass,  and  cover  it 
with  another  watch-glass. 

{h.)  The  heart  goes  on  beating.  Count  the  number  of  beats  per 
minute.  Therefore  its  beat  is  automatic,  and  the  heart  contains 
within  itself  the  mechanism  for  originating  and  keeping  up  iti 
rhythmical  beats. 


LII.]  THE   frog's   heart.  26 1 

(c.)  Place  the  heart  on  a  microscopical  slide  and  note  that  during 
diastole  it  is  soft  and  flaccid,  and  adjusts  itself  to  any  surface  it  may 
rest  on.  During  systole,  i.e.,  when  it  contracts,  its  apex  is  raised 
and  erected. 

6.  Heat  and  Cold  on  the  Excised  Heart. 

(a.)  Place  the  watch-glass  containing  the  beating  heart  on  the 
palm  of  the  hand,  and  the  heart  beats  faster  ;  or  place  it  on  a  beaker 
containing  warm  water,  which  must  not  be  above  40°  C.  Note 
that,  as  the  temperature  of  the  heart  rises,  it  beats  faster-- there  are 
more  beats  per  minute — therefore  each  single  beat  is  faster. 

{h.)  Place  the  watch-glass  and  heart  over  a  beaker  containing  iced 
water,  the  number  of  beats  diminishes,  each  beat  being  executed 
more  slowly  and  sluggishly. 

7.  Section  of  the  Heart. 

(a.)  Expose  the  heart,  divide  the  pericardium,  and  hgature  the 
frsenum,  and  by  means  of  it  gently  raise  the  heart.  With  scissors 
excise  the  whole  heart,  including  the  sinus  venosus.  The  heart  still 
beats. 

{h.)  Cut  off  the  sinus ;  it  continues  to  beat.  The  rest  of  the 
heart  ceases  to  beat  for  a  time,  but  by-and-by  it  commences  to  beat 
rhythmically. 

(c. )  Sever  the  auricles  from  the  ventricle ;  the  ventricle  ceases 
to  beat.  The  ventricle,  however,  has  not  lost  the  power  of  beating 
rhythmically.  To  prove  this,  stimulate  it  mechanically,  e.g.^  by- 
pricking  it  with  a  needle.  After  an  appreciable  latent  period,  it 
executes  one — generally  several — beats,  and  then  becomes  quiescent. 
Stimulate  with  a  single  induction  shock,  this  also  causes  it  to  dis- 
charge one  or  more  beats. 

{(J.)  Cut  ofi'  the  apex  of  the  ventricle  ;  it  remains  quiescent ;  but 
if  it  be  stimulated,  either  mechanically  or  electrically,  it  makes  a 
single  beat — not  a  series,  as  in  the  case  of  {(..). 

(e.)  Divide  the  ventricle  of  another  heart  below  the  auriculo- 
vcntricular  groove.  The  auricles,  with  the  upper  part  of  the  ventricle 
attached,  continue  to  beat,  while  the  lower  two-thirds  no  longer 
beats  spontaneously.  If  it  be  pricked  with  a  needle,  however,  it 
contracts  as  often  as  it  is  stimulated  mechanically.  It  responds  by  a 
single  contraction  to  a  single  stimulus,  but  a  single  stimulus  does 
not  excite  a  series  of  rhythmical  contractions. 

(J.)  With  scissors  divide  longitudinally  the  auricles  with  the 
attached  portion  of  the  ventricle.  Each  half  contracts  spontaneously, 
although  the  rhythm  may  not  be  the  same  in  both. 

{g.)  Instead  of  cutting,  one  may  use  a  ligature,  or  the  heart  apex_  may  be 
separated  by  Bernstein's  method,  viz.,  compress  the  heart  above  its  apex 


262  PRACTICAL  PHYSIOLOGY.  [LIII. 

by  forceps,  so  as  to  break  the  jthysiological  continuity  but  not  the  physical, 
both  parts  remaining  connected  with  each  other.  In  a  pulsating  heart,  all 
pulsates  except  the  apex.  It  the  bulbus  aorta;  be  compressed  so  as  to  raise 
the  pressure  within  the  apex,  the  apex  also  beats. 

8.  Movements  of  the  Heart. — Expose  the  heart  of  a  freshly 
pithed  frog  as  directed  in  Lesson  LII.,  or  better  still,  destroy  only 
the  brain  and  then  curarise  the  frog.     Observe 

(a.)  That  the  auricles  contract  synchronously  and  force  their 
blood  into  the  ventricle,  which,  from  being  pale  and  flaccid,  becomes 
red,  turgid,  and  distended  with  blood. 

(h.)  That  immediately  thereafter  the  ventricle  suddenly  contracts, 
and  forces  the  blood  into  the  bulbus  aortae,  at  the  same  time  becom- 
ing pale,  while  its  apex  is  tilted  forwards  and  upwards.  As  the 
auricles  continue  to  fill  during  the  systole  of  the  ventricle,  on 
superficial  observation  it  might  seem  as  if  the  blood  were  driven  to 
and  fro  between  the  auricles  and  ventricle,  but  careful  observation 
will  soon  satisfy  one  that  this  is  not  the  case.  Observe  very  care- 
fully how  the  position  of  the  auriculo-ventricular  groove  varies 
during  the  several  phases  of  cardiac  activity. 

(c.)  The  slight  contraction  of  the  bulbus  aortae  immediately 
follomng  the  ventricular  systole. 

(d.)  The  diastoHc  phase  or  pause  when  the  whole  heart  is  at  rest 
before  tlie  auricles  begin  to  contract.  Ligatiu-e  the  fraenum  and 
divide  it,  gently  raise  up  the  ventricle  by  the  ligature  attached 
to  the  fraenum,  and  observe  the  sinus  venosus. 

(e.)  The  peristaltic  wave,  or  wave  of  contraction,  begins  at  the 
upper  end  of  the  vena  cava  inferior  and  sinus  venosus ;  it  extends 
to  the  auricles,  which  contract,  then  comes  the  ventricular  systole 
and  that  of  the  bulbus  aortae,  and  finally  the  pause ;  when  the  whole 
sequence  of  events  begins  again  with  the  systole  of  the  sinus. 

(a.)  Before  the  ventricular  systole  is  complete  the  sinus  is  full, 
while  the  auricles  are  filling. 

All  this  is  easier  to  describe  than  to  observe,  and  it  requires 
patient  and  intelUgent  observation  to  assure  oneself  of  the  succes- 
sion of  eventa. 


LESSON  LIII. 

GRAPHIC   RECORD   OP   THE   PROG'S   HEART- 
BEAT— BPPECT   OP   TEMPERATURE. 

1.  Graphic  Eecord   of  the  Frog's  Heart   (Direct  registration 
with  lever). 

(a.)  Destroy  the  brain  of  a  frog ;  curarise  it     Expose  the  heart, 


LTII.] 


THE   frog's   heart-beat. 


263 


still  within  its  pericardium,  and  arrange  a  heart-lever  so  that  it  rests 
lightly  on  the  pericardium  over  the  beating  heart.  Adjust  the 
lever  to  write  on  a  revolving  cylinder,  moving  at  a  suitable  rate 
(5-6  cm.  per  second).     Take  a  tracing  of  the  beating  of  the  heart. 

(b.)  Before  commencing  the  experiment,  make  a  suitable  heart-lever  with 
a  straw  about  12  inches  long,  or  a  thin  strip  of  wood  about  the  same  len^'th. 
Thrust  a  needle  transversely  either  through  the  straw  or  through  a  piece  of 
cork  slipped  over  the  straw  about  2  inches  from  one  end  of  the  lever.  Tlie 
needle  forms  the  fulcrum  of  the  lever,  and  works  in  bearings,  whose  height 
can  be  adjusted.  To  the  end  of  the  lever  nearest  this  is  attached,  at  right 
angles,  a  needle  with  a  small  piece  of  cork  on  its  free  end.  The  lever  is  so 
adjusted  that  the  cork  on  the  needle  rests  on  the  heart.  The  long  arm  of  the 
lever  is  provided  with  a  writing-style  of  copper- foil,  or  a  writing  point  made 
of  parchment  paper,  fixed  to  it  with  sealing-wax.  By  using  a  long  lever  a 
sufficient  excursion  is  obtained.  Another  form  of  heart-lever  is  shown  in  fig. 
182.  It  consists  of  a  thin  glass  rod,  fixed  as  shown  in  the  figure.  The  frog  is 
laid  on  its  back  on  a  frog-plate  covered  with  cork.  The  heart-lever  is  fixed 
into  the  cork  by  means  of  the  two  pins  (6),  while  C  is  so  adjusted  as  to  rest  on 
the  heart. 


the 


Fio.  182.— Simple  Frog's  Heart-Lever,  a.  Fulcrum  ;  L.  Glass  lever  with  knob  to  act  as 
counterpoise  ;  b.  To  fix  the  apparatus  Into  the  cork  of  a  frog-plate  ;  C.  Cork  to  rest  on 
the  heart. 

(c.)  Open  the  pericardium,  expose  the  heart,  and  adjust  the 
cork  on  the  lever.  To  obtain  a  good  tracing,  it  is  well  to  put  a 
resistant  body  behind  the  heart.  Raise  the  ventricle,  ligature  the 
fraenum,  and  divide  the  latter  dorsal  to  the  ligature ;  behind 
heart  place  a  pad  of  blotting- 
paper  moistened  with  normal 
saline,  or  a  thin  glass-cover 
slip.  Adjust  the  cork  pad  of 
the  lever  on  the  junction  of 
the  auricles  and  ventricle,  to 
write  on  the  drum,  moving  at 
a  slow  rate  (5-6  cm.  per 
second),  and  take  a  tracing. 
Fix  the  tracing  (fig.  183). 

(d.)  In  the  tracing  note  a 
first  ascent,  due  to  the  auricular  contraction,  and  succeeding  this  a 
second  ascent,  due  to  the  contraction  of  the  ventricle,  followed  by 
a  slow  subsidence,  due  to  the  continuation  of  the  ventricular 
systole,  and  then  a  sudden  descent,  due  to  the  diastoHc  relaxation 
of  the  heart. 


Fig.  183.— Tracing  taken  with  a  Frog's  Heart- 
Lever  resting  on  the  Auriculo-ventiiciJlar 
Groove.  A.  Heart  tracing ;  T.  Time ;  each 
interval  represents  one  second. 


264  PRACTICAL   PHYSIOLOGY.  [LIIL 

2.  Auricular  Contraction. — Take  a  tracing  with  the  lever 
adjusted  on  the  auricles  alone,  and  avoid  the  bulbus  aortae.  Note 
the  smaller  excursion  of  the  lever. 

3.  Ventricular  Contraction. — Adjust  the  lever  so  as  to  obtain 
a  tracing  of  the  ventricular  movements  only. 

4.  lu  the  above  experiments  arrange  an  electro-magnetic  time- 
marker  or  chronograph  under  the  recording  lever,  so  that  the  poiuts 
of  tlie  recording  lever  and  time-marker  write  exactly  in  the  same 
vertical  line.  Thus  one  can  calculate  the  time-relations  of  any  part 
of  the  curve. 

5.  Effect  of  Temperature  on  the  Excised  Heart. 

-  (a.)  Excise  the  heart  of  a  pithed  frog,  lay  it  on  an  apparatus  like 
that  in  fig.  119.  Fix  india-rubber  tubes  to  the  inlet  and  outlet 
tubes  of  the  cooling-box,  the  inlet  tube  passing  from  a  funnel  fixed 


FlQ.  1S4.— Parts  of  a  Tracing  taken  from  an  Excised  Frog's  Heart.    The  temperature 
was  increased  gradually  from  left  to  right  of  the  curve. 

in  a  stand  above  the  box,  and  the  outlet  tube  discharging  into  a 
vessel  below  it.  Adjust  the  heart-lever  to  record  the  movements 
of  the  contracting  ventricle  on  a  slowly-revolving  drum.  If  the 
heart  tends  to  become  dry,  moisten  it  with  normal  saline  mixed 
with  blood.     Adjust  a  time-marker.     Take  a  tracing. 

(b.)  Pass  water  from  io°-2o°  C.  through  the  cooling-box,  noting 
the  effect  on  the  number  of  contractions,  and  the  duration,  height, 
and  form  of  each  single  beat. 

(0.)  The  heart  may  be  placed  on  a  metallic  support  and  gradually  heated 
by  means  of  a  spirit-lamp  or  other  means.  Fig.  184  shows  how  the  shape, 
size,  amplitude,  and  number  of  heart-beats  varies  with  a  rise  of  temperature, 
the  temperature  being  lowest  towards  the  left  end  of  the  tracing,  and  rising 
as  the  tracing  was  taken. 


liil] 


THE   FROGS   HEART-BEAT. 


265 


ADDITIONAL  EXERCISES. 
6.  Another  form  of  heart-lever  is  shown  in  fig.  185. 


Fig.  185.— Marey's  Heart-Lever,  as  made  by  Verdln. 

7.  In  order  to  record  simultaneously  the  contractions  of  auricles  and  ven- 
tricle, and  to  study  the  relations  of  these  events  one  to  the  other,  a  lever 
must  be  placed  on  the  auricles  and  another  on  the  ventricle,  and  the  points 


FlO.  t86.— Auricular  and  Ventricular  Lever  for  the  Heart  of  a  Turtle  or 
Tortoise.    Made  by  Verdin. 

of  both  must  be  arranged  so  that  the  one  writes  directly  over  the  other 
shown  in  fig.  186,  in  the  heart  of  a  turtle  or  tortoise. 


266 


PRACTICAL   PHYSIOLOGY. 


[UV. 


LESSON  LIY. 

SUSPENSION  METHODS  FOR  HEART— GASKBLL'S 
HEART-LEVER  AND  CLAMP. 

1.  Gaskell's  Heart-Lever  (Suspension  Methods). 

(a.)  This  lever  is  extremely  convenient  (fig.  187).     Expose  the 
heart  of  a  pithed  frog,  ligature  and  divide  the  frtenum,  tie  a  fine 

silk  thread  to  the.  apex  of 
the  ventricle,  and  attach  the 
thread  to  the  writing-lever 
placed  above  it.  The  lever 
is  kept  in  position  by  a  thin 
thread  of  elastic,  which 
raises  the  lever  after  the 
contraction  of  the  heart  has 
depressed  it. 

(b.)  Record  the  movements 
on  a  drum  moving  at  a 
slow  rate.  Record  time  in 
seconds. 

(c.)  First  the  auricles  con- 
tract and  pull  down  the 
lever  sUghtly,  then  the 
greater  contraction  of  the 
ventricle  pulls  the  lever 
down  further,  and  when  the 

EIG  187.— Showing  the  Arrangement  of  the  Frog  yentricle    relaxes,     the    lever 
and  Lever  for  a  Heart-Lever,  supported  by  a   .         .  i     l-    2.x.        j 

fine  elastic  thread.  IS  raised  by  the  elastic  tnreaa. 

Fig.  1 88  shows   tracing  ob- 
tained when  the  heart  is  free  and  no  clamp  is  applied. 


no.  i88.— Tracing  of  a  Frog's  Heart  taken  with  Apparatus  shown  in  Fig.  187. 
H.  Heai-t-tracing  ;  T.  Time  in  seconds. 

A  weak  spu-al  spring  may  be  used  instead  of  the  elastic  thread. 


LIV.] 


SUSPENSION   METHODS   FOR   HEART. 


267 


By  this  method,  also,  the  efifect  of  heat,  cold,  drugs  on  the  heart 
can  be  ascertained. 

N.B. — If  it  is  desired  to  ascertain  the  action  of  a  drug  on  the 
heart  by  this  method,  then  make  a  snip  in  the  heart  so  that  the 
blood  may  flow  out  and  the  drug  act  directly  on  the  cardiac 
muscle. 


2.  Varying  Speed  of  Cylinder  and  Effect  of  Temperature. 

{a.)  By  means  of  Gaskcll's  lever  record  the  form  of  the  heart- 
beat with  varying  rates  of  speed,  marking  time  in  seconds  in  each 
case  (fig.  189). 


Fia.  189.— Shows  how  Heart  Curve  varies  witn 
rate  of  Drum.  In  i,  2,  3,  T=  time  in  seconds. 
Gaskell's  Lever. 


FlO.  190. — Shows  the  effect  of  Normal  Saline 
directly  applied  to  the  Heart  (at  0°,  15' 
and  30°  C).  T  time  in  seconds.  Gaskell's 
Lever. 


{b.)  Then  ascertain  effect  of  temperature  on  the  rate  of  beat  and 
form  of  heart  curve  by  applying  normal  saline,  say  at  o°,  15°,  and 
30°  C,  directly  to  the  heart  (fig.  190). 

3.  Gaskell's  Clamp. 

(a.)  On  a  suitable  support  arrange  two  recording  long  light 
levers  of  the  same  length,  and  with  their  writing  points  exactly  in 
the  same  vertical  line,  recording  on  a  slow-moving  drum,  the  levers 
being  about  1 2  cm.  apart.     About  midway  between  the  two  place 


268 


PRACTICAL  PHYSIOLOGY. 


[liv. 


a  Gaskell's  clamp  (fig.  191,  C),  fixed  in  an  adjustable  arm  attached 
to  the  same  stand.  To  support  the  upper  lever,  fix  to  it  a  fine 
thread  of  caoutchouc  (E),  and  attach  the  latter  to  a  slit  or  other 
arrangement  on  the  top  of  the  support.     The  clamp  consists  of  two 

fine  narrow  strips  of  brass, 
like  the  points  of  a  fine  pair 
of  forceps,  which  can  be 
approximated  by  means  of  a 
screw. 

(b.)  Expose  the  heart  of  a 
pithed  frog.  Tie  a  fine  silk 
thread  to  the  apex  of  the 
ventricle,  and  another  to  the 
upper  part  of  the  auricles,  and 
excise  the  heart.  Tie  the 
auricular  thread  to  the  upper 
lever  and  the  ventricular  one 
at  a  suitable  distance  to  the 
lower  lever. 

(r,)  Adjust  the  clamp  (fig. 
191,  C)  so  as  to  clamp  the 
heart  in  the  auriculo- ventricu- 
lar groove,  but  at  first  take  care  not  to  tighten  it  too  much,  or 
merely  just  as  much  as  will  support  the  heart  in  position.  After 
fixing  the  heart  by  means  of  the  clamp,  fix  the  two  levers  so 
that  both  are  horizontal,  and  adjust  the  caoutchouc  thread  attached 


FlO.  19T.— Gaskell's  Clamp.  C  Heart  in  clamp  ; 
A.  Auricular,  and  V.  Ventricular  lever;  i'. 
Elastic  to  raise  A  after  it  is  pulled  down. 


FlO.  192.— Tracing  from  Auricle  (^1)  and  Ventricle  (F)  by  Oaskell's  Method. 
T.  Time  in  seconds. 


to  the  upper  one,  so  that  it  just  supports  the  upper  lever,  and  when 
its  elasticity  is  called  into  play  by  the  contracting  auricles  pulling 
down  the  lever,  it  will,  when  the  auricles  relax,  raise  it  to  the 
horizontal  position  again. 

(d,)  Adjust  a  time-marker  to  write  exactly  under   the  writing 


LIV.] 


SUSPENSION   METHODS   FOR   HEART. 


269 


points  of  the  two  levers.     Moisten  the  heart  from  time  to  time 
with  serum  or  dikite  blood. 

(e.)  After  obtaining  a  tracing  where  the  auricle  and  ventricle 
contract  alternately  (fig.  192),  screw  up  the  clamp  slightly  until 
the  ratio  of  auricular  to  ventricular  contraction  alters,  i.e.,  until, 
by  compressing  the  auriculo-ventricular  groove,  the  impulse  from 
the  auricles  to  the  ventricle  is  "  blocked "  to  a  greater  or  less 
extent,  when  the  auricles  will  contract  more  frequently  than  the 
ventricle. 

4.  Excised  Heart  (Gotch's  Arrangement). 

By  this  method  all  the  parts  are  fixed  to  a  X-piece  which  is 
clamped  in  a  stand,  so  that  the  whole,  preparation,  electrodes  and 
everything,  can  be  easily  adjusted  (fig.  193). 


PlO.  103.— Gotch's  Arrangement  for  Excised  Heart    All  parts  are  fixed  on  one  T-P^ece, 
T.P.    F.  Clamp-forceps  for  heart ;  C.  Cork  ;  L.  Lever. 


{a.)  Excise  a  frog's  heart,  suspend  it  by  clamp-forceps  (F)  to  a 
horizontal  rod  attached  to  a  y-piece  (T.P.).  On  the  -f-piece  is 
a  cork  into  which  the  electrodes  are  fixed,  while  the  heart  pulls  on 
a  counterpoised  lever. 

(/).)  By  means  of  this  arrangement  we  can  (i)  with  a  Stannius 
heart  show  (i.)  the  latent  period  of  cardiac  muscle  or  cardiac  delay, 
(ii.)  the  delay  of  transmission  of  an  impulse  from  auricle  to 
ventricle  in  the  groove ;  (2)  with  a  beating  heart,  the  refractory 
period,  rhythm,  inhibition  from  the  sinus  (crescent),  effect  of 
atropine,  muscarine,  &c. 

5.  Place  a  frog  on  a  crank-myograph,  attach  the  apex  of  the 
heart  still  in  situ  to  the  crank-lever  and  record  its  movements. 


270  PRACTICAL  PHYSIOLOGY.  [LV. 

6.  Writing  Point  of  Bayliss. — When  it  is  necessary  to  diminish 
friction  as  much  as  possible,  this  style  is  most  excellent.  Fix  to  a 
straw  a  piece  of  gummed  paper,  and  to  this  attach  a  bit  of  peritoneal 
membrJine  (same  as  is  used  for  oncometers)  and  a  bit  of  capillary 
glass  tube  fused  to  a  little  ball  at  the  end,  and  attached  to  the 
peritoneal  membrane  by  Front's  glue.  The  membrane  is  made 
broad  to  give  rigidity  in  the  direction  of  movement  of  the  lever. 

7.  Put  a  glass  tube  in  the  oesophagus  and  leave  the  heart  attached. 
Pass  water  at  different  temperatures  through  the  tube  and  observe  its  effect 
on  the  heart. 

(Engehnann,  "Versuche  am  suspendirten  HeTzen,"  Ffluger^s  Archiv.^  liL 
Ivi,  lix.  ;  Kaiser,  Zeits.  f.  Biol.,  xxxii.,  1895.) 


LESSON  LV. 


STANNIUS'S  EXPERIMENT— INHIBITION— LATBNl 
PERIOD  OF  HEART-MUSCLE, 

1.  Stannius's  Experiment.— Pith  a  frog,  and  expose  its  heart. 

(a.)  With  a  seeker  clear  the  two  aortas  from  the  auricles,  and  with 
an  aneurism  needle  pass  a  moist  silk  thread  between  the  two  aortas 
and  the  superior  venae  cavae ;  turn  up  the  apex  of  the  heart,  divide 
the  frsenum,  and  raise  the  whole  heart  to  expose  its  posterior 
surface,  and  the  crescent  or  Une  of  junction  of  the  sinus  venosus 
and  the  right  auricle.  Bring  the  two  ends  of  the  ligature  round 
the  heart — call  this  for  convenience  ISo.  1  Ugature — tie  them,  and 
tighten  the  ligature  just  over  the  "  crescent,"  so  as  to  constrict  the 
line  of  junction  of  the  sinus  venosus  with  the  right  auricle.  Befoie 
tightening  the  ligature,  observe  that  the  heart  is  beating  freely. 
On  tightening  the  ligature,  the  auricles  and  ventricle  cease  to  beat, 
and  remain  in  a  state  of  relaxation,  while  the  sinus  venosus  con- 
tinues to  beat  at  the  same  rate  as  before.  After  a  time,  if  left  to 
itself,  the  ventricle  may  begin  to  beat,  but  with  an  altered  rhythm. 
If  the  relaxed  ventricle  be  pricked,  it  executes  a  single  contraction, 
i.e.,  a  single  stimulation  produces  a  single  contraction. 

{h.)  When  the  heart  is  still  relaxed,  take  a  second  hgature  (Xo. 
2),  and  preferably  of  a  different  colour,  to  distinguish  it  from  No. 
I ;  place  it  round  the  heart,  and  tighten  it  over  the  an riculo- ven- 
tricular groove,  so  as  to  separate  the  ventricle  from  the  auricles. 
Immediately  the  ventricle  begins  to  beat  again,  while  the  auricles 
remain  relaxed  or  in  diastole. 


LV.]  STANNIUS'S  EXPERIMENT.  2/1 

(c.)  Instead  of  applying  No.  2  ligature,  the  ventricle  may  be  cut 
oflf  from  the  auricles  by  means  of  a  pair  of  scissors.  Immediately 
after  it  is  amputated,  the  ventricle  begins  to  beat.  Stannius  liga- 
ture is  of  practical  importance  (i.)  for  arresting  the  uninjured 
ventricle  to  measure  its  electro-motivity  (Lesson  XLYI.),  (ii.)  for 
ascertaining  the  latent  period  of  cardiac  muscle  (p.  272)  (Hofmann, 
"  Function  d.  Scheidewandnerven  d.  Froschherzens,"  Pjiiiger's 
Archiv.y  Bd.  60,  p.  139). 

2.  Staircase  Character  of  the  Heart-Beats. 

Stannius  a  heart  as  above,  i.e.,  arrest  the  beating  of  the  auricles 
and  ventricle  by  tightening  a  ligature  over  the  sino-auricular  groove. 
Attach  the  apex  of  the  heart  by  means  of  a  silk  thread  to  a  record- 
ing lever,  as  in  fig.  187,  and  record  on  a  slow-moving  drum. 

The  heart  is  quiescent.  Stimulate  it  with  a  single  induction 
shock  at  intervals  of  5  seconds.  Notice  that  the  first  beat  is 
lower  than  the  second,  the  second  than  the  third,  so  that  each  beat 
exceeds  its  predecessor  in  amplitude  until  a  maximum  beat  is 
obtained.  The  amount  of  increase  gradually  decreases  towards  the 
end  of  the  series.     This  is  the  "  Staircase  "  of  Bowditch. 

3.  Intracardiac  Inhibitory  Centre. 

(a.)  Expose  the  heart  in  a  pithed  frog,  tie  a  fine  silk  ligature 
round  the  frsenum,  and  divide  the  latter  between  the  ligatured 
spot  and  the  pericardium.  Gently  raise  the  whole  heart  upwards 
to  expose  the  somewhat  whitish  V-shaped  "  crescent "  between  the 
sinus  venosus  and  the  right  auricle. 

(b.)  Arrange  previously  an  induction  coil  for  repeated  shocks. 
Place  the  electrodes — which  must  be  fine,  and  their  points  not  too 
far  apart  (2  millimetres) — upon  the  crescent,  and  faradise  it  for  a 
second ;  if  the  current  be  sufficiently  strong,  after  a  period  of  delay, 
the  auricles  and  ventricle  cease  to  beat  for  a  time,  but  they  begin 
to  beat  even  in  spite  of  continued  stimulation.  The  electrodes  are 
conveniently  supported  on  a  short  cylinder  of  lead.  They  can  be 
fixed  to  the  lead  by  modeller's  wax. 

(c.)  Stimulate  the  auricles  ;  there  is  no  inhibition  or  arrest. 

(d.)  Apply  a  drop  of  sulphate  of  atropine  solution  (Lesson  LVIL, 
1)  to  the  heart.  Stimulation  of  the  crescent  no  longer  arrests  the 
heart.     The  atropine  paralyses  the  inhibitory  fibres  of  the  vagus. 

4.  Inhibitory  (Crescent)  Arrest  Recorded. 

(a.)  Take  a  tracing  with  Gaskell's  lever.  Stimulate  the  crescent 
for  1-2  seconds  with  induction  shocks  as  in  3,  and  observe  the 
arrest  of  the  heart's  beat  (fig.  194).     In  the  primary  circuit  place 


272  PRACTICAL   PHYSIOLOGY.  [LV. 

a  small  electro-magnetic  signal.  This  will  begin  to  vibrate  when 
the  primary  circuit  is  closed,  and  mark  the  period  of  stimulation  as 
a  white  patch  on  the  black  surface.  Make  its  point  record  exactly 
under  the  heart-lever.     Take  a  time-tracing  in  seconds. 

(b.)  After  a  pause  the  beat  begins,  the  contraction  travelling 
as  a  wave  from  sinus,  through  auricles  to  ventricle. 

(f.)  Stimulate  the  auricles.  During  inhibition  the  sinus  beats, 
but  the  auricles  and  ventricle  do  not,  because  the  excitabihty  of  the 
auricles  is  so  lowered  that  they  do  not  propagate  the  excitatory 
process. 

(d.)  Stimulate  the  ventricle  mechanically,  the  heart  beats  in  the 
reverse  order  from  ventricle,  auricles  to  sinus. 


FlO.  194. — Arrest  of  the  Frog's  Heart- Beat  by  Electrical  Stimulation  of  the  Crescent. 
See.  Time  in  seconds ;  H.  Heart-beats ;  S.  Stimulation. 

5.  Seat  of  the  Motor  Centres. 

(a.)  Expose  a  pithed  frog's  heart,  cut  out  the  ventricle  with  the  auricles 
attached  to  it,  and  observe  that  the  heart  continues  to  beat.  Divide  the 
ventricle  vertically  by  two  parallel  cuts  into  three  portions.  The  middle 
portion  contains  the  auricular  septum,  in  which  lie  ganglionic  cells.  It  con- 
tinues to  beat  while  the  right  and  left  lateral  parts  do  not  beat  spontaneously, 
but  respond  by  means  of  a  single  contraction  if  they  are  stimulated. 

6.  Latent  Period  of  Cardiac  Muscle  (Cardiac  Delay). — This  is 
ascertained  in  the  same  way  as  in  a  skeletal  muscle,  but  there  is  this 
difference,  the  heart  beats  rhythmically  while  the  skeletal  muscle 
is  at  rest  until  excited.  Therefore  the  heart-beat  must  be  brought 
to  a  standstill.     This  can  be  done  by  a  Stannius  hgature. 

{a.)  Arrange  an  induction  coil  to  give  single  shocks,  putting  in 
the  primary  coil  an  electro-magnet  which  records  its  movement  on 
a  slow-revolving  drum.  This  will  indicate  the  moment  of  stimu- 
lation. 

(h.)  Expose  the  heart  in  a  pithed  frog,  "  Stannius "  its  heart 
(Lesson  LV.).  This  will  arrest  its  beat.  Then  tie  a  silk  thread  to 
the  apex  of  the  ventricle,  and  attach  the  thread  to  a  Gaskell's  heart- 
lever.  Arrange  the  heart-lever  so  that  it  records  on  a  drum  exactly 
above  the  electro-magnet. 


LVI.]  CARDIAC   VAGUS   OF  THE   FROG.  2/3 

(c.)  Adjust  a  lever  marking  time  in  seconds  exactly  over  the 
electro-magnet  lever. 

(d.)  There  will  be  recorded  two  horizontal  lines ;  stimulate  Avith 
a  single  induction  shock, — the  moment  of  stimulation  will  be 
indicated  by  the  second  lever,  and  shortly  after,  the  heart  will 


FlQ.  195.— Tracing  of  Staiiniused  Heart  of  Frog,  stimulated  at  S  with  a  single  Maximum 
Induction  Shock.    T.  Time  in  seconds.    Gaskell's  Lever. 

respond ;  the  interval  represents  the  "  latent  period  " — which  may 
be  about  half  a  second  according  to  temperature  and  other  con- 
ditions (fig.  195). 

(e,)  Stimulate  the  auricle  and  observe  the  longer  "  delay  " ;  the 
wave  of  contraction  takes  longer  to  travel,  and  is  delayed  at  the 
groove. 


LESSON  LVI. 


CARDIAC  VAGUS  AND  SYMPATHETIC  OP  THE 
FROG  AND  THEIR  STIMULATION. 

1.  Cardiac  Vagus  of  the  Frog — To  Expose  it. — Make  a  pre- 
liminary dissection  before  attempting  to  stimulate  tlie  vagus. 

Pith  a  frog,  or  destroy  its  brain  and  curarise  it.  Lay  it  on 
its  back  on  a  frog-plate.  Expose  the  heart,  remove  the  sternum 
and  pull  the  fore-legs  well  apart.  Introduce  a  small  test-tube  or 
stick  of  sealing-wax  into  the  oesophagus  to  distend  it ;  the  nerves 
leaving  the  cranium  are  better  seen  winding  round  from  Ijchind 
when  the  oesophagus  is  distended.  Remove  the  muscles  covering 
the  petrohyoid  muscles,  which  reach  from  the  petrous  bone  to  the 
posterior  horn  of  the  hyoid  bone  (fig.  196).  Three  nerves  are  seen 
coursing  round  the  pharynx  parallel  to  these  muscles.  Tlie  lowest 
is  the  hypoglossal  (Hg),  easily  recognised  by  tracing  it  forward  to 

8 


274 


PRACTICAL   PHYSIOLOGY. 


[lvl 


the  tongue,  above  it  is  the  vagus  in  close  relation  with  a  blood- 
vessel (V),  and  still  further  forward  is  the  glosso-pharyngeal  (GP). 
Observe  the  laryngeal  branch  of  the  vagus  (L).  The  vagus,  as 
exposed  outside  the  cranium,  is  the  vago-sympathetic.  The 
glosso-pharyngeal  and  vagus  leave  the  cranium  through  the  same 
foramen  in  the  ex-occipital  bone,  and  tlirough  the  same  foramen 
the  sympathetic  enters  the  skulL 

2.  Stimulation  of  the  Cardiac  Vagus. 

(a.)  Adjust  a  Gaskell's  heart^lever  to  record  the  contractions  of 
the  heart  on  a  revolving  drum  moving  at  a  slow  rate. 


SM-- 


—ou. 


FlO.  196.— Scheme  of  the  Dissection  of  the  Frog's  Vagus.  SM.  Submentalis :  LW.  Lnng; 
V.  Vagus;  GP.  Glosso-pharyngeal;  Ug.  Hypoglossal;  L.  Laryngeal;  PU,  SH,  GU, 
OH.  Petro-,  Sterno-,  Genio-,  Omo-hyoid ;  HB.  Hyoid ;  HQ.  Hyoglossus ;  H.  Heart; 
BR.  Brachial  plexus. 


(h.)  Place  well-insulated  electrodes  under  the  trunk  of  the  vagus. 
Take  a  normal  tracing,  and  then  stimulate  the  vagus  with  an  inter- 
rupted current,  and  observe  that  the  whole  of  the  heart  is  arrested 
in  diastole.  The  best  form  of  electrodes  is  the  fine  shielded  elec- 
trodes shown  in  fig.  227,  Although  the  faradisation  is  continued, 
the  heart  recommences  beating.  The  arrest,  or  period  of  inhihi- 
tio)},  is  manifest  in  the  curve  by  the  lever  recording  merely  a 
straight  line.     If  the  laryngeal  muscles  contract,  and  thereby  affect 


lvl]       cardiac  vagus  of  the  frog.       275 

the  position  of   the   heart,   divide  the  laryngeal  branches  of  the 
vagus. 

(c.)  Note  that  when  the  heart  begins  to  beat  again,  the  beats  are 
small  at  first  and  gradually  rise  to  normal.  In  some  instances, 
however,  they  are  more  vigorous  and  quicker  (fig.  197). 

3.  Latent  Period  or  Delay  of  Vagus. — For  this  purpose  a  time- 
marker  and  an  arrangement  to  indicate  when  the  stimulus  is  thrown 
into  the  nerve  are  required. 

{a,)  Arrange  the  heart-lever  as  before,  and  adjust  a  time-marker 
to  write  exactly  under  the  heart-lever. 

(b.)  Arrange  an  induction  coil  for  repeated  shocks,  and  keep 
Neef's  hammer  vibrating.  Into  the  secondary  circuit  introduce  an 
electro-magnet  with  a  writing-lever  attached  to  it ;  so  adjust  the 
electro-magnet  that  its  writing-style  writes  exactly  under  the  heart- 
lever,  and  arrange  that  when  the  writing-style  on  the  e\,ectro-magnet 

-VWVWWVN  p^^W 

a  1 1  u  I  u  I  HI  I  n  1 1  li'  1 1 1  n  1 1 1 1  HI  m  1 1 1  |i  n  11  u  I  i  u  1 1 1 1 1  n  1 1 1 1 
:  I  Time  m  Seoa« 

I j 

I        Stimulation  I 


Fia.  197.— Vagus  Curve  of  Frog's  Heart. 

is  depressed — e.g.,  by  means  of  a  weight — the  secondary  circuit  is 
short-circuited,  so  that  no  stimulus  is  sent  along  the  electrodes  under 
the  trunk  of  the  vagus. 

(c.)  When  all  is  ready,  Hft  the  weight  off  the  electro-magnet, 
whereby  the  secondary  current  is  un-short-circuited,  the  electro- 
magnet lever  rises  up,  records  its  movements  on  the  cylinder,  and 
at  the  same  moment  the  induction  shocks  are  sent  through  the 
V  igus.  Observe  that  the  heart  is  not  arrested  immediately,  but  a 
certain  time  elapses — the  latent  period — usually  about  one  beat  of 
the  heart  (1*5  sec),  before  the  heart  is  arrested." 

{d.)  Short-circuit  the  secondary  current  again,  and  observe  how 
the  heart  gradually-  resumes  its  usual  rhythm— sinus  venosus, 
auricles,  and  ventricle. 

{'-.)  Repeat  {c.)  several  times,  noting  that  the  heart  after  arrest 
goes  on  beating  in  spite  of  continued  stimulation. 

(/'.)  An  electro-magnet  may  be  introduced  into  the  primary 
circuit  to  mark  the  moment  of  stimulation  just  as  in  Lesson  LIV.  6. 

4.  Action  of  the  Sympathetic  on  the  Heart  of  the  Frog. 
{a.)  Pitli  a  frog,  or  jtreferably  a  toad,  cut  away  the  lower  jaw,  and  continue 
the  slit  from  the  angle  ot  the  mouth  downwards  for  a  short  distance.     Turn 


276 


PRACTICAL  PHYSIOLOGY. 


[lvi. 


the  parts  well  aside,  and  expose  the  vertebral  column  where  it  joins  the  skull. 
Remove  the  mucous  membrane  covering  the  roof  of  the  mouth.  The  sym- 
pathetic is  found  before  it  joins  the  vagus  emerging  from  the  cranium  (fig. 
198).  Carefully  isolate  the  sympathetic.  It  lies  immediately  under  the 
levator  anguli  scapulae,  which  must  be  carefully  removed  with  fine  forceps, 
when  the  nerve  comes  into  view,  usually  lying  under  an  artery.  The  nerve 
is  usually  pigmented.  Put  a  ligature  round  it  as  far  away  from  the  skull  as 
practicable,  and  cut  the  nerve  below  the  ligature. 


Fia.  198.— Scheme  of  the  Frog's  Sympathetic.  LAS.  Levator  angnli  8C«pul»;  Sym. 
Sympathetic;  GP.  Glosso-pharyngeal ;  VS.  Vago-gympathetic ;  Q.  Ganglion  of  the 
vagus ;  Ao.  Aorta ;  SA.  Subclavian  artery  (Gaskelt). 


{b.)  Expose  the  heart  and  attach  its  apex  to  a  lever  supported  by  an  elastic 
thread  as  in  Gaskell's  method.  Record  several  contractions,  and  then  stimu- 
late the  sympathetic  with  weak  interrupted  shocks  by  means  of  fine  electrodes. 
The  heart  beats  quicker.  If  the  heart  is  beating  quickly,  reduce  the 
number  of  beats  by  cooling  it  with  ice. 

(c.)  If  desired,  the  vagus  may  be  isolated  and  stimulated,  and  the  effects  of 
the  two  nerves  compared  (although  the  vagus  outside  the  skull  is  really  the 
vagosympathetic). 

Stimulation  of  the  intracranial  vagus— I'.g.,  before  it  is  joined  by  the 
sympathetic — is  somewhat  too  difficult  for  the  average  student,  and  is  there- 
fore omitted  here. 

N.B. — It  is  important  to  note  that  the  effect  of  vagus  stimulation  on  the 
heart  varies  with  the  season  of  the  year,  and  is  often  different  in  the  two  vagi. 
In  some  animals  one  vagus  is  inactive. 


LVII.]  DRUGS  AND  CURRENT  ON    HEART.  27^ 


LESSON  LVII. 

DRUGS  AND  CONSTANT  CURRENT  ON  HEART 
—DESTRUCTION  OF  CENTRAL  NERVOUS 
SYSTEM. 

1.  Action  of  Drugs  on  the  Heart— Muscarine,  Atropine,  and 
Nicotine. — Either  the  excised  heart,  placed  in  a  watch-glass,  or  the 
heart  in  situ  may  be  used,  or  Gotch's  method  may  be  employed 
(p.  269).  The  heart  may  be  attached  to  a  Gaskell's  lever  (fig.  187) 
and  the  result  recorded.  The  last  is  the  best  plan,  for  by  this  means 
a  tracing  can  readily  be  obtained. 

(a.)  Muscarine.— Pith  a  frog,  expose  its  heart,  and  if  desired 
attach  its  apex  to  a  Gaskell's  lever  recording  its  movements.  Record 
the  result  (fig.  199).  To  get  the  full  effect  of  the  drug  on  cardiac 
action  snip  the  heart  to  allow  the  blood  to  run  out.  With  a  fine 
pipette  apply  a  few  drops  of  serum  or  normal  saline  (0.6  p.c.)  con- 
taining a  trace  of  muscarine,  which  rapidly  arrests  the  rhytlimical 
action  of  the  heart,  the  ventricle  being  relaxed — i.e.,  in  diastole — 
and— if  uncut— distended  with  blood.  Before  it  stands  still  tlie 
heart-beats  become  less  and  less  vigorous.  (This  is  a  good  method 
of  collecting  a  considerable  quantity  of  frog's  blood  when  it  is 
wanted  for  any  purpose  from  the  heart.) 

(6.)  When  the  ventricle  is  completely  relaxed  in  the  diastolic 
phase,  it  is  very  inexcitable,  responding  only  to  strong  stimuli,  and 
perhaps  the  auricles  not  at  all. 

Atropine. — To  the  heart  arrested  with  muscarine, 

{c.)  After  a  few  minutes,  with  another  pipette  apply  a  few  drops 
of  a  0.5  per  cent,  solution  of  sulphate  of  atropia  in  normal  saline. 
The  heart  gradually  again  begins  to  beat  rhythmically.  Thus  tlie 
atropine  undoes  the  effect  of  the  muscarine.  This  is  sometimes 
spoken  of  as  "  Antagonistic  action  "  of  drugs  (fig.  199). 

{d.)  Faradise  the  crescent  or  inhibitory  centre  of  the  atropinised 
heart;  the  heart  is  no  longer  arrested,  because  the  atropine  has 
paralysed  the  intracardiac  inhibitory  mechanism. 

{e.)  Pilocarpine. — In  another  frog,  arrest  the  action  of  the  heart 
with  pilocarpine,  and  then  apply  atropine  to  antagonise  it,  observing 
that  the  heart  beats  again  after  the  action  of  atropine. 

(/.)  Nicotine. — Apply  nicotine  (.2  milligram).  Stimulation  of 
the  vagus  no  longer  arrests  the  heart's  action,  but  stimulation  of  the 
sinus  venosus  does  ;  so  that  nicotine  paralyses  the  fibres  of  the 
vagus,  and  leaves  the  intracardiac  inhibitory  mechanism  intact. 


278 


PRACTICAL  PHYSIOLOGY. 


[LVIL 


2,  Constant  Current  on  the  Heart. 

(a.)  Pith  a  frog.  Cut  out  the  heart,  dividing  it  below  the 
auricido- ventricular  groove,  thus  obtaining  an  "  apex  "  preparation 
which  does  not  beat  spontaneously. 


Fig.  199.— Tracing  of  Heart  attached  to  Gaskell's  Lever,  arrested  by  ifnscarine.  and 
Rhytlim  restored  by  Atropine.  J/.  Muscarine  effect ;  A.  Atropine  applied  ,  T.  Time 
in  seconds. 

(h.)  By  means  of  seahng-wax,  fix  a  cork  to  a  lead  base  5  cm. 
square,  cover  the  upper  end  of  the  cork  with  sealing-wax,  and 
thrust  through  it  two  wires  to  serve  as  electrodes,  about  4  mm. 
apart  (fig.  200),  or  by  means  of  sealing-wax  fix  two  fine  wires  upon 
an  ordinary  microscopic  glass  slide  to  act  as  electrodes.  Cover  the 
wliole  with  a  beaker  lined  with  moist  blotting-paper.  Place  the 
heart  apex  with  its  base  against  one  electrode,  and  its  apex  against 
the  other. 


FlO.  200.— Support  for  Frog's  Heart. 
E.  Electrodes  ;  H.  Heart. 


Fig.  201. — Stairca.se  Character 
of  Heart-Beat. 


(c.)  Arrange  two  Dani ell's  cells  in  circuit,  connect  them  with 
a  key,  and  to  the  latter  attach  the  electrodes.  Pass  a  continuous 
current  in  the  direction  of  the  apex.  The  heart  resumes  its 
rhythmical  beating,  and  continues  to  do  so  as  long  as  the  constant 
current  passes  through  the  living  preparation. 

3.  The  Staircase. 

(a.)  To  a  microscopical  glass  slide  (3x1)  fix  witli  sealing-wax  two  copper 
wires  in  the  long  axis  of  the  slide,  their  ft-ee  ends  being  about  3  millimetres 


LVIIL]  PERFUSION   OF   FLUIDS.  2/9 

apart.  They  will  act  as  electrodes.  Connect  the  other  ends  of  the  wires  tc 
a  Du  Bois  key  introduced  into  the  secondary  circuit  of  an  induction  machine. 
Arrange  the  primary  coil  for  single  induction  shocks,  introducing  a  Morse 
key  in  the  circuit. 

{b.)  Make  an  "apex  preparation,"  and  place  it  on  the  electrodes  on  the 
glass  slide.  Rest  on  the  heart  a  heart-lever  properly  balanced  and  arranged 
to  record  its  movements  on  a  slow-moving  drum  (5  mm.  per  second).  The 
preparation  does  not  contract  spontaneously,  but  responds  to  mechanical  or 
electrical  stimulation. 

(c.)  Stimulate  the  apex  preparation  with  single  break  induction  shocks  at 
intervals  of  about  ten  seconds.  To  do  this,  un -short-circuit  the  secondary 
circuit,  depress  the  Morse  key,  short-circuit  the  secondary  circuit,  and  close 
the  Morse  key  again.  Repeat  this  at  intervals  of  ten  seconds,  and  note  that 
the  amplitude  of  the  second  contraction  is  greater  than  the  first,  that  of 
the  third  than  the  second,  the  fourth  than  the  tliird,  and  then  the  successive 
beats  have  the  same  amplitude  (fig.  201).  Allow  the  heart  a])ex  to  rest  for  a 
few  minutes,  and  repeat  the  stimulation.  Always  the  same  result  is  obtained. 
From  the  graduated  rise  of  the  first  three  or  four  beats  after  a  period  of  rest, 
the  phenomenon  is  known  as  the  "staircase,"  The  increment  is  not  equal 
in  each  successive  beat,  but  diminishes  from  the  beginning  to  the  end  of  the 
series. 

(d.)  If,  while  the  apex  is  relaxing,  it  be  stimulated  by  a  closing  shock,  it 
contracts  again,  so  that  the  lever  does  not  immediately  come  to  the  abscissa, 

(e.)  li  the  Morse  key  be  rapidly  tapped  to  interrupt  the  primary  current, 
the  contractions  become  more  or  less  fused,  and  the  lever  remains  above  the 
abscissa  writing  a  sinuous  line. 

4.  Effect  of  Destruction  of  the  Nervous  System  on  the  Heart  and  Vas- 
cular Tonus. 

{a.)  Destroy  the  brain  of  a  frog,  and  expose  its  heart  in  the  usual  way, 
taking  care  to  lose  no  blood  ;  note  how  rod  and  full  the  heart  is  with  blood. 

(6.)  Suspend  the  frog,  or  leave  it  on  its  back,  introduce  a  stout  ])in  into  tlio 
spinal  canal,  destroy  the  spinal  cord,  and  leave  the  pin  in  the  canal  to  prevent 
bleeding.  Observe  that  the  heart  still  continues  to  beat,  but  it  is  }»(lc  and 
collapsed,  and  apparently  empty ;  it  no  longer  fills  with  blood.  The  blood 
remains  in  the  greatly  dilated  abdominal  blood-vessels,  and  does  not  return 
to  the  arterial  system,  so  that  the  heart  remains  without  blood.  Il  the  belly 
be  opened,  the  abdominal  veins  are  seen  to  be  filled  with  blood. 

(c.)  Amputate  one  limb,  perhaps  not  more  than  one  or  two  drops  of  blood 
will  be  shed,  while  in  a  frog  with  its  spinal  cord  still  intact,  blood  flows  freely 
after  amputation  of  a  limb. 


LESSON  LVIII. 


PERFUSION  OF  FLUIDS  THROUGH  THE  HEART 
—PISTON-RECORDER. 

1.  Perfusion  of  Fluids  through  the  Heart. 
The  Fluid. — (a.)  Take  two  volumes  of  normal  saline,  add  one 
volume   of  defibrinated  sheep's   blood,  mix,  and  filter.     See  that 


28o 


PRACTICAL  PHYSIOLOGY. 


[lviii. 


the  blood  is  tlioroughly  shaken  up  with  air  before  mixing  it.     This 
is  the  best  fluid  to  use. 

{/>.)  Ringer's  Fluid. — Take  99  cc.  of  .6  per  cent.  NaCl  solution, 
saturate  it  with  calcic  phosphate,  and  add   I  cc.  of  a  i  per  cent.       | 
solution  of  potassic  chloride.  « 

(e.)  Rub  up  in  a  mortar  4  grams  of  dried  ox-blood  (this  can  be  purchased) 
with  60  cc.  of  normal  saHne.  Allow  it  to  stand  some  time,  add  40  cc.  of 
water,  and  filter. 

2.  Preparation  of  the  Heart. 

((I.)  Pith  a  frog,  expose  its  heart,  ligature  and  divide  the  frsenum 
behind  the  ligature. 

(h.)  Take  a  two-wayed  cannula  (fig.   202),  attach   india-rubber 
tubing  to  each  tube,    and  fill    the  tubes   and  cannulae   with   the 
fluid  to  be  perfused.     Pinch  the  india-rubber 
tubes  with  fine  bull  dog  forceps  to  prevent  the 
escape  of  the  fluid. 

(r.)  Tie  a  fine  thread  to  the  apex  of  the 
ventricle.  To  this  thread  a  writing-lever  is  to 
be  attached. 

(d.)  P>y  means  of  the  frgenum  ligature  raise 
the  heart,  with  a  pair  of  scissoi-s  make  a  cut 
into  the  sinus,  and  through  the  opening  intro- 
duce the  double  cannula  passed  through  a 
cork,  until  its  end  is  well  within  the  ventricle. 
Tie  it  in  with  a  ligature,  the  hgature  constrict- 
ing the  auricles  above  the  auriculo-ventricular 
groove,  thus  making  what  is  known  as  a 
"  heart-preparation."  Cut  out  the  heart  with 
its  cannula. 
(e.)  In  a  filter-stand  arrange  a  glass  funnel,  with  an  india-rubber 
tube  attached,  at  a  convenient  height  (6-7  inches  above  the  heart), 
fill  it  with  the  perfusion  fluid,  clamp  the  tube.  Attach  this  tube 
to  one  of  the  tubes — the  inflow — connected  with  one  stem.of  the 
cannula,  taking  care  that  no  air-bubbles  enter  the  tube.  Adjust 
the  height  of  the  reservoir  so  that  the  fluid  can  flow  freely  through 
t}ie  heart,  and  pass  out  by  the  other  tube  of  the  cannula.  Place  a 
vessel  to  receive  the  outflow  fluid.  After  a  short  time  the  heart 
will  begin  to  beat. 

(/■.)  Place  the  heart  in  a  cylindrical  glass  tube,  fixed  on  a  stand, 
and  arranged  so  that  the  cork  in  which  the  cannula  is  fixed  fits 
into  the  mouth  of  the  tube.  A  short  test-tube  does  perfectly 
well.  The  lower  end  of  the  glass  tube  has  a  small  aperture  in  it 
through  which  the  thread  (c)  is  passed,  and  attached  to  a  writing- 
lever  arranged  on  the  same  stand  as  the  glass  vessel     See  that 


Fig.  202.  —  Kronecker's 
Cannula  for  Frog's 
Heart. 


LIX.]  ENDOCARDIAL   PRESSURE.  28 1 

the  lever  is  horizontal,  and  writes  freely  on  a  slow-moving  recording 
drum.  Every  time  tlie  heart  contracts  it  raises  the  lever,  and  during 
diastole  the  lever  falls  (fig.  203). 

In  this  way  it  is  possible  to  use  various  fluids  for  perfusion.  The 
fluids  may  be  placed  in  separate  reservoirs,  each  communicating 
with  the  inlet  tube,  and 
capable  of  being  shut  off  or 
opened  by  clamps  as  re- 
quired. Furtlier,  by  poison- 
ing the  supply  fluid  with 
atropine,  muscarine,  sparte- 
ine, or  other  drug,  one  can 
readily  ascertain  the  effect 
of  these  drugs  on  the  heart, 
or   the   antagonism   of    one 

j^„      ,             ,1  Fig.  203.  -  Tracing  obtained  from  a  Frog's  Heart, 

arug  to  anOUier.  througli  which  Dilute  Blood  was  perfused.  The 

Instead  of   a   glass  funnel           contrnctin-  heart  raised  a  registering  lever. 

-^     ^ ,  n    •  1             The  lower  line  indicates  seconds. 

as  a  reservoir  for  the  fluid, 

one  may  use  a  Marriotte's  flask  (fig.  204),  the  ^ad vantage  being  that 
the  pressure  of  the  fluid  in  the  inflow  tube  is  constant.  Another 
simple  arrangement  is  to  have  a  bird's  water-bottle,  with  a  curved 
tube  leading  from  it  to  the  inflow  tube  of  the  cannula. 

3.  Piston-Recorder  (of  Schafer). 

The  heart  is  tied  to  a  two-way  cannula  as  before,  and  is  intro- 
duced into  a  horizontal  tube  with  a  dilatation  on  it.  The  tube  of 
the  recorder  is  filled  with  oil,  and  as  the  heart  dilates  it  forces  the 
oil  along  the  tube  and  moves  a  light  piston  resting  on  it.  When 
systole  takes  place,  the  oil  recedes,  and  with  it  the  piston.  The 
piston  records  on  a  slow-moving  drum  placed  horizontally  and 
gives  excellent  results. 


LESSON  LIX. 


ENDOCARDIAL  PRESSURE— APEX  PREPARATION 
—TONOMETER. 

1.  Endocardial  Pressure  in  the  Heart  of  a  Frog. 

(a.)  Proceed  as  in  tlie  previous  experiment  {a.),  (b.)  (omit  c),  (d.). 

{b.)  Arrange  a  frog's  mercury  manometer  provided  with  a  writing-style  as 
in  fig.  204.  Attacli  the  inlet  tube  of  the  cannula  to  tlie  Marriotte's  flasks 
(a,  b),  and  connect  the  outflow  with  the  tube  of  the  mercury  manometer.  It 
is  well  to  have  a  j-tube  between  the  iieart  and  the  manometer,  but  in  tin' 
heart  apparatus,  as  shown  and  used,  the  exit  tube  is  preferable.     See  that 


282 


PRACTICAL  PHYSIOLOGY. 


[lix. 


no  air-bubbles  are  present  in  the  system.  Every  time  the  heart  contracts 
the  mercury  is  displaced  and  the  writing  style  is  raised,  and  records  its  move- 
ments on  a  slow- moving  drum. 

(r.)  Take  a  tracing  with  the  outflow  tube  and  Marriotte's  flask  shut  ofi",  so 
that  the  whole  efi"ect  of  the  contraction  of  the  heart  is  exerted  upon  the 
mercury  in  the  manometer.  Take  another  tracing  when  the  fluid  is  allowed 
i.0  flow  continuously  through  the  heart.  The  second  Marriotte's  flask  shown 
in  the  figure  is  for  the  perfusion  of  fluid  of  a  different  nature,  and  by  means 
of  the  stojKJOck  (s)  one  can  pass  either  the  one  fluid  or  the  other  through  the 
heart.  The  little  cup  {d)  under  the  heart  can  be  raised  or  lowered,  and  filled 
with  the  nutrient  fluid,  and  in  it  the  heart  is  bathed. 


2.  Apex  Preparation. — In  this  pre- 
paration of  the  heart  only  the  apex 
of  the  heart  is  used.  As  a  rule,  it 
does  not  beat  spontaneously  until 
suflBcient  pressure  is  api)lied  to  its 
inner  surface  by  the  fluid  circulating 
through  the  heart. 

(a.)  Proceed  as  in  Lesson  LVIII.  2 
(a.),  (b.)  (omit  c),  {d.),  with  this 
difference,  that  in  {d.)  the  cannula 
is  placed  deeper  into  the  ventricle, 
and  the  ligature  is  tied  round  the 
ventricle  below  the  auriculo-ventricu- 
lar  groove.  Excise  the  heart  and 
cannula,  and  attach  it  to  the  heart 
apparatus  as  in  the  previous  experi- 
ment. 

(6.)  If  the  "heart  a])ex"  prepara- 
tion does  not  contract  spontaneously, 
stimulate  it  by,  e.g.,  single  induction 
shocks,  either  make  or  break.  To 
this  end  adjust  an  induction  machine, 
the  wires  from  the  secondary  coil  being 
attached,  one  to  the  cannula  itself, 
while  the  other  is  placed  in  the  fluid 

in  the  glass  cup,  into  which  the  heart  is  lowered. 

(c.)  By  introducing  an   electro-magnet  with   a  recording  lever  into  the 

primary  circuit,  and  having  a  time-marker  recording  at  the  same  time,  one 

can  detennine  the  latent  period  of  the  apex  preparation.     It  is  about  0.15 

sec. 
(d.)  If  desired,  the  eff'ect  of  a  constant  current  may  be  studied  in  this  way 

instead  of  by  the  method  described  in   Lesson  LVI.    2.     The  apex  beats 

rhythmically  under  the  influence  of  the  constant  current. 


Fia.  204.— Scheme  of  Kronecker'8  Frog 
nanometer. 


3.  Roy's  Frog-Heart  Apparatus  or  Tonometer. — This  apparatus  registers 
the  change  of  volume  of  the  contracting  heart.  Fig.  205  shows  a  scheme  of 
the  apparatus,  and  fig.  206  the  apparatus  itseli.  The  apparatus  consists  of  a 
small  bell-jar,  resting  on  a  circular  brass  plate  about  2  inches  in  diameter, 
and  fixed  to  a  stand  adjustable  on  an  upright.  In  the  biass  plate  are  two 
openings,  the  small  one  leads  into  an  outlet  tube  (e),  provided  with  a  stop- 
cock. The  other  is  in  the  centre  of  the  plate,  and  leads  into  a  short  cylinder 
1  cm.  in  length  by  i  cm.  in  internal  diameter.  A  groove  runs  round  the  out- 
side of  this  cylinder  near  its  lower  edge,  to  permit  of  a  membrane  being  tied 


LIX.] 


ENDOCARDIAL  PRESSURE. 


283 


on  to  it.  In  this  cylinder  works  a  light  alnnunium  piston  (p),  slightly  less  in 
diameter  than  the  cylinder.  Aronnd  the  lower  aperture  of  the  cylinder  is  tied 
a  piece  of  flexible  animal  membrane,  the  liga- 
ture resting  in  the  grooved  collar.  The  free 
I)art  of  the  membrane  is  tied  to  the  piston,  from 
the  centre  of  whose   under-surface  (;>)  a  needle 

f)asses  down  to  be  attached  to  a  light  writing- 
ever  (/)  fixed  below  the  stage.  The  bell-jar  is 
filled  with  oil  {o),  while  in  its  uj)per  opening  is 
fitted  a  short  glass  stoj)iier,  })ertbrated  to  allow 
the  passage  of  a  two-wayed  heart-cannula  with 
the  heart  attached  (A).  In  using  the  instrument 
proceed  as  follows  : — 

(a.)  Fix    the    bell-jar    to    the   circular   brass 

plate  by  the  aid  of  a  little  stiff  grease.     Tie  a 

piece   of  the  delicate   transparent  membrane  — 

such  as  is  used  by   perfumers   for  covering  the 

corks  of  bottles — in  the  form  of  a  tube   round 

the  lower  end  of  the 

grooved       cylinder ; 

y  afterwards  the  lower 

.L .  end  of  the  membrane 

is  fixed  to  the   pis- 
ton, taking  care  that 


FlQ.  205. — Scheme  of  K.oy's  Tonometer. 


the  needle  attached  to  the  piston  hangs  towards  the  recording  lever.     Drop 
in  a  little  glycerin  to  moisten  the  membrane. 


FlO.  206.— Hoy's  Tonometer,  as  made  by  the  Cambridge  Scientific 
Instrument  Company. 

(b.)  Fill  the  jar  with  olive-oil,  and  have  the  recording  apparatus  ready 
adjusted.     Prepare  the  heart  of  a  large  frog  [Lesson  LVIIL  (a.),  {b.)  (omit  c), 


284  PRACTICAL  PHYSIOLOGY.  [LX. 

('/.>]  the  cannula  used  being  one  fixed  in  the  glass  stopper  of  the  bell-jar,  and 
attiich  the  inlet  tube  of  the  cannula  to  the  reservoir  of  nutrient  fluid,  while 
the  outlet  tube  is  arranged  so  as  to  allow  fluid  which  has  passed  through  the 
heart  to  drop  into  a  suitable  vessel. 

(c. )  Intro«iuce  the  cannula,  with  the  heart  attached,  into  the  oil,  and  see 
that  the  stopper  is  securely  fixed.  Open  the  stopcock  (g1,  and  allow  some  oil 
to  flow  out  of  0,  thus  rendering  the  pressure  within  sub-atmospheric  ;  and  as 
soon  as  the  pressure  has  fallen  sufficiently,  and  the  little  piston  is  gradually 
drawn  up  to  the  proper  height,  close  the  stopcock.  Attach  the  needle  of  the 
piston  to  the  recording  light  lever,  and  take  a  tracing. 


LESSOX  LX. 


HEART-VALVES— ILLUMINATED  HEART— STETHO- 
SCOPE—CARDIOGRAPH— POLYGRAPH -MEIO- 
CARDIA  —  REFLEX  INHIBITION  OP  THE 
HEART. 

1.  Action  of  Heart- Valves. — This  is  of  value  in  order  that  the 
student  may  obtain  a  knowledge  of  the  mechanical  action  of  the 
valves.  The  heart  and  lungs  of  a  sheep  —with  the  pericardium  still 
unopened — must  he  procured  from  the  butcher. 

(a.)  Open  the  pericardium,  observe  its  reflexion  round  the 
blood-vessels  at  the  base  of  the  heart.  Cut  off  the  lungs  moderately 
wide  from  the  heart.  Under  a  tap  wash  out  any  clots  in  the  heart 
by  a  stream  of  water  entering  through  both  auricles.  Prepare  from 
a  piece  of  glass  tubing,  1 5  mm.  in  diameter,  a  short  tube,  8  cm.  in 
length,  with  a  flange  on  one  end  of  it,  and  another  about  60  cm. 
long.     Fix  a  ring  to  hold  a  large  funnel  on  a  retort  stand. 

(b.)  Tie  the  short  tube  into  the  superior  vena  cava,  the  flanged 
end  being  inserted  into  the  vessel.  It  must  be  tied  in  with  well- 
waxed  stout  twine.  In  the  pulmonary  artery  (P. A.) — separated 
from  its  connections  with  the  aorta,  which  lies  behind  it — tie  the 
long  tube,  the  flange  securing  it  completely.  Ligature  the  inferior 
vena  cava,  and  the  left  azygos  vein  opening  into  the  right  auricle. 
Connect  the  short  tube  by  means  of  india-rubber  tubing  with  tlie 
reservoir  or  funnel  in  the  retort  stand.  Keep  the  level  of  the 
water  in  the  funnel  below  the  upper  surface  of  the  P.  A.  tube.  Fill 
the  funnel  with  water ;  it  distends  the  right  auricle,  passes  into 
the  right  ventricle,  and  rises  to  the  same  height  in  the  P.  A.  tube 
as  the  level  of  the  fluid  in  the  funnel.  Compress  the  right  ventricle 
with  the  hand  ;  the  fluid  rises  in  the  P.  A.  tube  ;  and  observe  on 
relaxing  the  pressure  that  the  fluid  remains  stationary  in  the  P.  A. 
tube  as  it  is  supported  by  the  closed  semilunar  valves.     If  the  right 


LX.]  HEART-VALVES.  285 

ventricle  be  compressed  rliytlimically,  the  fluid  will  rise  higher  and 
higher,  until  it  is  forced  out  at  the  top  of  the  P.A.  tube,  and  a 
vessel  must  be  held  to  catch  it.  Observe  that  the  column  of  fluid 
is  supported  by  tlie  semilunar  valves,  and  above  tlic  position  of  the 
latter  observe  the  three  bulgings  corresponding  to  the  position  of 
the  sinuses  of  Valsalva. 

(c.)  Repeat  {!>.),  if  desired,  on  the  left  side,  tying  the  long  tube 
into  the  aorta,  and  the  short  tube  into  a  pulmonary  vein,  ligaturing 
the  others. 

(d.)  Cut  away  all  the  right  auricle,  hold  the  heart  in  the  left 
hand,  and  pour  in  water  from  a  jug  into  the  tricuspid  orifice.  The 
water  runs  into  the  right  ventricle,  and  floats  up  the  three  cusps  of 
the  tricuspid  valve  ;  notice  how  the  three  segments  come  into  apposi- 
tion, while  the  upper  surfaces  of  the  valves  themselves  are  nearly 
horizontal. 

(e.)  With  a  pair  of  forceps  tear  out  one  of  the  three  segments  of 
the  semilunar  valve  of  the  P.A.  Tie  a  short  tube  into  the  P. A., 
and  to  it  attach  an  India  rubber  tube  communicating  with  a  funnel 
supported  on  a  retort  stand.  Pour  water  into  the  funnel,  and 
observe  that  it  flows  into  the  right  ventricle,  floats  up,  and  securely 
closes  the  tricuspid  valve.  The  semilunar  valves  have  been 
rendered  incompetent  through  the  injury.  Turn  the  heart  any  way 
you  please,  there  is  no  escape  of  fluid  through  the  tricuspid  valve. 

(/.)  Take  a  funnel  devoid  of  its  stem  and  with  its  lower  orifice 
surrounded  by  a  flange,  and  tie  it  into  the  aorta.  Cut  out  the  aorta 
and  its  semilunar  valves,  leaving  a  considerable  amount  of  tissue 
round  about  it.  Place  the  funnel  with  the  excised  aorta  in  a  filter 
stand,  and  pour  water  into  the  funnel ;  much  of  it  will  escape 
througli  the  coronary  arteries ;  ligature  these.  The  semilunar 
valves  are  quite  competent,  i.e.,  they  allow  no  fluid  to  escape 
between  their  segments.  Hold  a  lighted  candle  under  the  valves, 
and  observe  through  the  water  in  the  funnel  how  they  come 
together  and  close  the  orifice ;  observe  also  the  triradiate  lines,  and 
the  lunules  in  apposition  projecting  vertically. 

(//.)  Slit  open  the  P. A.,  and  observe  the  form  and  arrangement 
of  the  semilunar  valves. 

[T.S,  Ventricles.— Make  a  transverse  section  through  both 
ventricles,  and  compare  the  shape  of  the  two  cavities  and  the 
relative  thickness  of  their  respective  walls. 

Casts  of  Heart. — Study  t\vo  casts  of  the  heart-ventricles  (by 
Ludwig  and  Hesse),  (i)  in  diastole,  and  (2)  in  systole. 

Effect  of  Ligature. — Ligature  any  large  vessel  attached  to  the 
heart ;  one  feels  the  sensation  of  something  giving  way  when  the 
ligature  is  tightened.  Cut  away  the  ligature,  open  the  blood-vessel, 
and  observe  the  rupture  of  the  coats  produced  by  the  ligature.] 


286 


PRACTICAL  PHYSIOLOGY. 


[lx. 


2.  Illuminated  Ox-Heart  (Gad). 

This  must  be  arranged  previously  by  the  demonstrator.  Two 
brass  tubes  with  glass  windows  are  tied,  one  into  the  left  auricle  {d) 
(7  cm.  diameter)  and  the  other  {<:)  into  the  aorta  (5  cm.  diameter). 
These  are  connected  with  a  large  reservoir  (R),  as  shown  in  the 
figure.  The  interior  of  the  heart  is  illuminated  by  a  small  elec- 
tric lamp  if)  pushed  in  through  the  apex  of  the  heart,  and  served 

by  several  small  Grove  cells. 
Into  the  apex  is  tied  a  brass 
tube,  which  is  connected  with 
a  large  india-rubber  bag  with 
thick  walls  (P).  Fill  the  whole 
with  water.  On  compressing 
the  elastic  bag,  fluid  is  driven 
onwards,  when  the  play  of 
the  valves  can  be  beautifully 
studied.  On  relaxation,  the 
mitral  valves  open  and  the 
aortic  valves  close. 

After  each  demonstration, 
remove  the  glass  windows  of 
the  cannulse  and  the  caout- 
chouc tubes,  and  preserve 
the  heart  in  10  p.c.  chloral 
hydrate. 


Fig.  207.— Scheme  of  Gad's  Apparatus  to  show 
the  play  of  the  Valves  of  the  Heart.  A.  L. 
auricle ;  d.  Its  window,  and  communicating 
with  b,  the  inlet  tube  for  water  from  the 
reservoir,  R;  V.  L.  ventricle,  illuminated  by 
an  electric  lamp,  I,  and  communicating  with 
the  elastic  bag,  P ;  e.  Glass  window  fixed  in 
tube  in  aorta  ;  a.  Tube  carrying  fluid  to  the 
reservoir. 


3.     The    Stethoscope  — 
Heart  Sounds. 

{a.)  Place  the  patient  or 
fellow-student  in  a  quiet 
room,  and  let  him  stand 
erect  and  expose  his  chest. 
Feel  for  the  cardiac  impulse, 
apply  the  small  end  of  the 
stethoscope  over  this  spot,  and  apply  the  ear  to  the  opposite  end  of 
the  instrument.  The  left  hand  may  be  placed  over  the  carotid  or 
radial  artery  to  feel  the  pulse  in  either  of  those  arteries ;  compare 
the  time-relations  of  the  pulse  with  what  is  heard  over  the  cardiac 
impulse. 

{h.)  Two  sounds  are  heard — the  first  or  systolic  coincides  with 
the  impulse,  and  is  followed  by  the  second  or  diastolic.  After  this 
there  is  a  pause,  and  the  cycle  again  repeats  itself.  The  first  sound 
is  longer  and  deeper  than  the  second,  which  is  of  shorter  duration 
and  sharper, 

(c.)  Place  the  stethoscope  over  different  parts  of  the  praecordia, 


LX.] 


HEART-VALVES. 


287 


noting  that  the  first  sound  is  heard  loudest  at  the  apex  beat,  while 
the  second  is  heard  loudest  at  the  second  ridit  costal  cartilage  at 
its  junction  with  the  sternum. 

4.  Cardiograph. — Several  forms  of  this  instrument  are  in  use, 
including  those  of  Marey,  B.  Sanderson,  and  the  pansphygmograph 
of  Brondgeest.     Use  any  of  them. 

(a.)  Place  the  patient  on  his  back  with  his  head  supported  on  a 
pillow.  Feel  for  the  cardiac  impulse  between  tlie  fifth  and  sixth 
ribs  on  the  left  side,  and  about  half  an  inch  inside  the  mammar}^ 
line. 

{/).)  Arrange  the  cardiograph  by  connecting  it  (fig.  208)  with 
thick-walled  india-rubber  tubing  to  a  recording  Marey's  tambour 
adjusted  to  write  on  a  drum  (fig. 
150).  It  is  well  to  have  a  valve 
or  a  y-tube  capable  of  being 
opened  and  closed  between  the 
receiving  and  recording  tambours, 
in  order  to  allow  air  to  escape  if 
the  pressure  be  too  great. 

(r.)  Adjust  the  ivory  knob  of 
the  cardiograph  (/>)  over  the  car- 
diac impulse  where  it  is  felt  most, 
and  take  a  tracing.  Fix,  varnish, 
and  study  the  tracing  or  cardio- 
gram. P 

FlO.  208.— Marey's  Cardiograph,  p.  Button 

5.  Efifect  of  SwallOwioe:  on  the  ^^^^^^  V^^'  ^^^''^'iac  impulse  :  s.  Screw 
__  .  -r»  .  /n«-  s  to  regulate  the  projection  of  p  ;  t. 
Heart-Beats  (Man).  Tube  to  other  tambour. 

With  a  watch  in  front  of  you, 
count  the  number  of  your  own  pulse-beats  per  minute,  and  then 
slowly  sip  a  glass  of  water,  still  keeping  your  finger  on  the  pulse. 
Count  the  increase  in  the  number  of  pulse-beats  during  the 
successive  acts  of  swallowing.  This  is  due  to  the  inhibitory  action 
of  the  vagus  being  set  aside. 

6.  Reflex  Inhibition  of  the  Heart  (Rabbit). 

Place  one  hand  over  the  chest  of  a  rabbit  and  feel  the  beating  of 
the  heart.  With  the  other  hand  suddenly  close  its  nostrils,  or 
bring  a  little  ammonia  near  the  nostrils,  so  as  to  cause  the  animal 
to  close  them.  Almost  at  once  the  heart  is  felt  to  cease  beating 
for  a  time,  but  it  goes  on  again. 

7.  Goltz's  Tapping  Experiment  (Frog). 

(a.)  Destroy  the  cerebrum  and  optic  lobes  of  a  frog.  Pin  it  out  on  a  frog- 
plate,  and  expose  its  heart,  or  attach  the  heart  to  a  Gaskell's  lever.     Exposa 


288 


PRACTICAL  PHYSIOLOGY. 


[lx. 


the  intestines  and  tap  theni  s^ve'-il  times  with  the  handle  of  a  scalpel.  The 
heart  ceases  to  beat  lor  a  time,  being  arrested  reflcxly.  The  afferent  nerve 
is  the  sympathetic  from  t\ie  abdomen,  and  the  efferent  the  vagus.     The 


tappinff  succeeds  more  promptly  if  the  intestines  are  slightly  inflamed  by 
exposure  to  the  air. 

{b.)  It  suflaces  to  exert  digital  pressure  over  the  abdomen  to  produce  thia 
reflex  arrest  of  the  heart. 


LX.] 


HEART-VALVES. 


289 


ADDITIONAL  EXERCISES. 

8.  Polygrapn  of  Knoll  and  Rothe. — This  is  a  most  convenient  apparatus, 
both  for  work  in  the  laboratory  and  at  the  bedside.  Moreover,  it  is  so 
arranged  that  two  tracings  can  be  taken  simultaneously.  It  is  made  by 
H.   ;^the,   Wenzelbad,   Prague.      It  can  be  used  to  take  simultaneously 


Fia.  210.— U.  Tracing  of  the  cardiac  impulse,  the  respiratory  movements  of  the  chect 
not  being  arrested. 

cardiac  im])ulse  and  a  pulse  tracing,  or  respiratory  movements  and  a  pulse 
tracing,  or  two  ])ulse  tracings. 

Fig.  209  shows  the  ariangement  of  the  apparatus.     It  consists  of  a  drum 
[*  F)  moved  Ity  clockwork  within  the  box  D.     K  is  a  catch  for  setting  D  in 


FiCk  an.— Showing  the  Method  of  Fixing  the  K«ceivlng  Tambour  of  Eothe's 
Polygraph  on  an  Artery. 

motion.  M  is  a  time-marker  beating  seconds.  H,  H  are  two  Marey*8 
registering  tambours  adjustable  on  the  stand  C.  B  is  a  tambour  which  can 
be  fixed  over  an  artery  or  over  the  cardiac  impulse,  while  A  is  a  bottle-shaped 
caoutchouc  bag  which  can  be  strapped  to  the  body  for  studying  the  respiratory 
movements. 


290 


PRACTICAL  PHYSIOLOGY. 


[lx. 


(a.)  Adjust  the  tambour  (B)  over  the  cardiac  impulse,  and  fix  the  bag  (A) 
on  the  abdomen  so  as  to  record  simultaneously  the  cardiac  impulse  and  the 
respirations  (fig.  210).  The  experimenter  may  also  take  a  tracing  of  the 
cardiac  impulse  wliile  the  respiration  is  arrested. 


Fig.  212.— p.  Tracing  of  radial  pulse;  /?.  EasplratlonB;  T,  Time  In  seconda, 

{h.)  Take  a  tracing  of  the  radial  pulse  and  the  respiratory  movements. 
Fig.  211  shows  how  the  receiving  tambour  is  adjusted  over  an  artery.  At 
the  same  time  record  the  respirations,  and  note  in  the  tracing  (fig,  212)  how 


FlO.  213. 


-P.  Tracing  of  the  radial  pulse ;  H.  Of  the  cardiac  impulao; 
T.  Time  in  seconds. 


the  nuiftber  and  form  of  the  pulse-beats  vary  during  inspiration  and  expira* 
tion — the  number  being  greater  during  inspiration. 

(c.)  Take  a  tracing  of  the  radial  piJse  and  the  cardiac  impulse  simultane. 
ously  (fig.  213). 


lxl]  pulse,  291 

9.  Meiocardia  and  Auxocardia  (Ceradini). 

(a.)  Bend  a  glass  tube  about  20  mm.  in  diametei  into  a  semicircle,  with 
a  diameter  of  about  6-8  inches.  Taj)er  off  one  end  in  a  gas- flame  to  fit  a 
nostril,  and  draw  out  the  other  end  of  the  tube  to  about  the  same  size. 
Round  off  the  edges  of  the  glass  in  a  gas-flame. 

(b.)  Fill  the  tube  with  tobacco-smoke,  place  one  end  of  it  in  one  nostril, 
close  the  other  nostril,  cease  to  breathe,  but  keep  the  glottis  open.  Observe 
that  the  smoke  is  moved  in  the  tube,  passing  out  in  a  small  puff  during 
auxocardia,  i.f.,  when  the  heart  is  largest;  while  it  is  drawn  farther  into 
the  tube  during  meiocardia,  i.e.,  when  the  heart  is  smallest. 

These  movements,  sometimes  called  the  * '  cardio-pneumatic  movements," 
are  due  to  the  variations  of  the  size  of  the  heart  during  its  several  phases  at 
fulness  altering  *he  volume  of  air  in  the  lungs. 


LESSON  LXI. 


PULSE— SPHYGMOGRAPHS—SPHYGMOSCOPE— 
PLETHYSMOGRAPH. 

1.  The  Pulse. 

(a.)  Feel  the  radial  pulse  of  a  fellow-student,  count  the  number 
of  beats  per  minute  ;  compare  its  characters  with  your  own  pulse, 
including  its  volume  and  compressibility.  Observe  how  its  charac- 
ters and  frequency  are  altered  by  (i)  muscular  exercise;  (2)  a 
prolonged  and  sustained  deep  inspiration ;  (3)  prolonged  expira- 
tion ;  and  (4)  other  conditions. 

(/;.)  Feel  the  radial  pulse-beat  and  heart-beat  (the  latter  over  the 
cardiac  impulse)  simultaneously.  Note  that  the  former  is  not 
synchronous  with  the  latter,  the  pulse-beat  at  the  wrist  occurring 
about  ^  second  after  the  heart-beat,  i.e.,  the  pulse-wave  takes  this 
time  to  travel  from  the  heart  to  the  radial  artery. 

(r.)  Ivisten  to  the  heart-sounds  at  the  same  time  that  the  radial 
pulse  is  being  felt.  Note  that  the  pulse  is  felt  after  the  first  sound 
about  midway  between  the  first  and  second  sounds. 

(r/.)  By  appropriate  recording  apparatus  one  can  readily  show 
that  the  pulse  is  not  simultaneous  throughout  the  arterial  system : 
thus  the  carotid  precedes  the  femoral,  &c. 

2.  Sphygmograph.— Many  forms  of  this  instrument  are  in  use. 
Study  the  forms  of  Marey  and  Dudgeon. 

Marey's  Sphygmograph  (fig.  2 1 4) — Application  of. 

(a.)  Cause  the  patient  to  seat  himself  beside  a  low  table,  and 
place  his  forearm  on  the  double-inclined  plane  (fig.  214),  which, 
in  the  improved  form  of  the  instrument,  is  the  Hd  of  the  box  so 


292 


PRACTICAL  PHYSIOLOGY. 


[lxl 


made  as  to  form  tliis  plane.  The  fingers  are  to  be  semiflexed,  so 
that  the  back  of  the  wrist,  resting  on  the  plane,  makes  an  angle 
of  about  30°  with  the  dorsal  surface  of  the  hand. 

(b.)  Mark  the  position  of  the  radial  artery  with  ink  or  an  aniline 


Fig.  214.— Marey's  Sphygraograph  applied  to  the  Ann. 

pencil.  Wind  up  the  clock  (H),  apply  the  ivory  pad  of  the  instru- 
ment exactly  over  the  radial  artery  where  it  lies  on  the  radius,  and 
fix  it  to  the  arm  by  the  non-elastic  straps  (K,  K).  The  sphygmo- 
graph  must  be  parallel  to  the  radius,  and  the  clockwork  next  the 
elbow.  Cover  the  sHde  with  enamelled  paper,  smoke  it,  fix  it  in 
position,  and  arrange  the  writing-style  (C')  to  write  upon  the 
smoked  surface  (G)  with  the  least  possible  friction.     Regulate  the 


FlO.  215.— Tracing  taken  from  the  Radial  Art*ry  by  means  of  Harey'a  Sphygmograph. 
A.  A  hard,  and  B,  a  softer  pulse. 

pressure  upon  the  artery  by  means  of  the  milled  head  (L),  i.e., 
until  the  greatest  amplitude  of  the  lever  is  obtained. 

('■.)  Set  the  clockwork  going,  and  take  a  tracing.     Fix  it,  write 
the  name,  date,  and  pressure,  and  study  the  tracing  (fig.  215). 


LXI.] 


SPHYGM0GRAPH3. 


293 


FlQ  218-  Lud  wig's  Sphygmograph,  made  by  Petzold  of  Leipzig. 


294 


PRACTICAL   PHYSIOLOGY. 


[LXL 


3.  Dudgeon's  Sphygmograph  (fig.  216). 

Adjust  the  instrument  on  the  radial  artery  by  means  of  an 
elastic  strap,  carefully  regulating  the  pressure — which  can  be  gradu- 
ated from  1-5  ounces — by  means  of  the  milled  head.  Smoke 
the  band  of  paper,  insert  it  between  the  rollers,  and  take  a  tracing. 
Study  the  tracing  (fig.  217). 


¥I9.  aig. — Ludwig's  Support  for  Arm  for  the  Sphygtnograpli. 

4.  Ludwig's  Sphygmograph. —Use  this  instrument  (fig.  218). 
It  is  not  unlike  a  Dudgeon's  sphygmograph,  but  there  is  a  frame 
adapted  to  the  arm,  and  an  arrangement  for  keeping  the  arm  steady 
while  the  hand  grasps  a  handle  for  the  purpose. 

By  the  device  shown  in  fig.  219  the  arm  is  kept  quite  steady 
and  always  in  the  same  position.  In  fact,  we  find  it  most  con- 
venient for  taking  tracings  with  either  Dudgeon's  or  Ludwig's 
sphygmograph.  It  has  also  been  found  most  valuable  for  clinical 
work.     It  is  made  by  Petzold  of  Leipzig. 


ADDITIONAL  EXERCISES. 

5.  Action  of  Amyl  Nitrite. 

{a.)  With  the  sphygmograph  adjusted,  take  a  tracing,  and  then  place  tioo 
drops — not  more — of  amyl  nitrite  on  a  handkerchief,  and  inhale  the  vapour. 


LXII.] 


RIGID  AND   ELASTIC  TUBES. 


295 


Within  fifteen  to  thirty  seconds  or  thereby  it  will  affect  the  pulse,  lowering 
the  tension,  the  tracing  presenting  all  the  characters  of  a  soft-pulse  tracing, 
with  a  well-marked  dicrotic  wave. 

6.  Gag  Sphygmoscope  (fig.  220). 

Connect  the  inlet  tube  of  the  instrument  with  the  gas  supply,  light  the 
gas-flame  (6).  Apply  the  caoutchouc  membrane  (a)  over  the  radial  artery, 
and  observe  how  the  flame  rises  and  falls  with  each  pulse-beat.  Take 
expiration,  and  observe  the  dicrotism  in  the  gas-flame. 


Fig.  220.— SigmuBd  Mayer's  Gas  Sphygmoscope,  made  by  Rothe  of  Prague. 

7.  Plethysmograph.  —Use  the  air-piston  recorder  of  Ellis,  and  take  a 
plethysmographic  tracing  of  the  variations  of  the  volume  of  a  finger.  The 
piston  of  the  recorder  must  be  lubricated  with  an  essential  oil,  e.g.,  clove. 

8.  Delepine's  Gas  Sphygmoscope  is  convenient.  {Brit,  Med.  Jour.,  July 
1891.) 

9.  Influence  of  the  Respiration  on  the  Pulse. 

(i.)  Miiller's  Experiment.— Close  the  mouth  and  nostrils  and  then  make 
a  forced  prolonged  inspiratory  effort.  Before  doing  so,  feel  the  pulse,  and 
keep  feeling  it.  Note  now  the  cessation  of  the  pulse-beat.  The  intra- 
thoracic vessels  are  filled  with  blood,  and  the  distended  auricles  are  unable 
to  contract. 

(ii.)  Valsalva's  Experiment. — Make  the  experiment  as  before,  but  make 
a  prolonged  vigorous  expiration.     Note  fall  in  pulse-beats. 


LESSON  LXII. 


RIGID     AND     ELASTIC     TUBES  —  PULSE-WAVE — 
SCHEME  OP  THE  CIRCULATION— RHEOMETER. 


1.  Rigid  and  Elastic  Tubes. — To  the  vertical  stem  of  a  glass 
U-tube  or  three-way  tube,  i  cm.  in  diameter,  fix  an  elastic  pump 
whose  opposite    end  dips   into  a  vessel  of   water.     To  the  othei 


296  PRACTICAL  PHYSIOLOGY.  [LXII. 

slightly  curved  ends  of  the  tiihe  fix  a  glass  tuhe,  90  cm.  or  thereby 
in  length,  and  to  the  open  end  of  the  tube  attach  a  small  short 
piece  of  india-rubber  tubing  with  a  clamp  over  it.  To  the  other 
limb  attach  an  india-rubber  tube  of  the  same  diameter  and  length 
as  the  glass  tube,  and  fix  a  clamp  over  its  outflow  end.  Pump 
water  through  the  system.  The  pump  may  be  compressed  directly 
by  the  hand,  or  it  may  be  placed  between  the  two  blades  of  a 
"  lemon-squeezer,"  and  the  extent  of  the  excursion  of  the  latter 
regulated  by  a  screw. 

(a.)  Rigid  Tube. — Clamp  off  the  elastic  tube  near  the  U-piece. 
"Work  the  pump  about  forty  beats  per  minute,  and  force  water  into 
the  glass  tube.  The  water  flows  out  in  jefs  in  an  intermittent 
stream  corresponding  to  each  beat.  Gradually  clamp  the  outflow 
tube,  and  keep  pumping ;  the  water  still  flows  out  in  an  intermit- 
tent stream,  and  no  amount  of  diminution  of  the  outflow  orifice 
will  convert  it  into  a  continuous  stream ;  as  much  water  flows  out 
as  is  forced  in.  All  that  happens  is,  that  less  flows  out,  and,  of 
course,  less  enters  the  tube.  Instead  of  the  clamp  at  the  outflow, 
a  tube  drawn  to  a  fine  point  may  be  inserted. 

(/>.)  Elastic  Tube.— Clamp  ofi"  the  glass  tube  near  the  U-piece, 
and  unclamp  the  flexible  one  so  as  to  have  no  resistance  at  its  out- 
flow end.  AVork  the  pump;  the  outflow  takes  place  in  jets  cor- 
responding to  each  beat  of  the  pump.  Pump  as  rapidly  as  possible 
and  the  outflow  stream  will  still  be  intermittent.  While  pumping, 
gradually  clamp  the  tube  at  its  outflow  so  as  to  introduce  resistance 
there — to  represent  the  resistance  in  the  small  arterioles—  and  when 
there  is  sufficient  resistance  at  the  outflow,  the  stream  becomes  a 
uniform  and  rontinu"us  one.  Feel  the  tube ;  with  each  beat  a 
pulse-beat  is  felt.  The  resistance  at  the  periphery  brings  the 
elasticity  of  the  tube  into  play  between  the  beats,  and  thus  con- 
verts the  interrupted  into  a  uniform  flow.  This  apparatus  serves 
also  to  demonstrate  M-hy  there  is  no  pulse  in  the  capillaries,  and 
under  what  circumstances  a  pulse  is  propagated  into  the  capillaries 
and  veins. 

2.  Velocity  of  the  Pulse-Wave, 

{n.)  Take  3  metres  of  india-rubber  tubing  6  mm.  in  diameter.  To  one  end 
of  the  tube  attach  the  ball  of  a  Hiorginson's  syringe  (elastic  ])unip)  to  imitate 
the  heart,  while  the  other  end  of  the  tube  is  left  open,  with  a  clamp  lightly 
fixed  on  it.  Arrange  to  ])um})  water  through  the  tube.  Arrange  two  light 
levers  on  one  stand,  and  place  a  jiart  of  the  tube  near  the  jmmp  under  the 
lower  lever,  and  resting  on  a  suitable  sup]>ort,  while  part  of  the  tube  near 
the  outflow  end  is  similarly  arranged  under  the  upper  lever.  Regulate  the 
pressure  of  the  lever  uiK)n  the  tube  by  means  of  lead  weights. 

{b.)  Arrange  on  the  same  stand  a  Despretz's  chronograph  to  record  the 
vibrations  of  an  electro-tuning-fork  (30  or  50  D.V.  per  second),  with  the 
writing  jwints  of  the  two  levers  and  chronograph  writing  upon  the  drum  in 
the  same  vertical  line. 


LXTI.]  RIGID   AND   ELASTIC  TUBES.  297 

(c.)  Set  the  tuning-fork  vibrating,  allow  the  drum  to  move,  compress  the 
elastic  pump  interruptedly— to  imitate  the  action  of  the  heart — and  propel 
water  through  the  tube.  The  compression  may  be  done  by  means  of  a  lemon- 
squeezer,  the  extent  of  the  excursion  being  regulated  by  a  screw,  and,  to 
secure  regularity,  arrange  the  number  of  pulsations  to  the  beating  of  a 
metronome.  On  doing  so,  as  one  pumps  in  water,  the  tube  distends  and 
raises  the  lever ;  in  the  interval  between  the  beats,  as  the  water  flows  out 
at  the  other  end,  the  tube  becomes  smaller,  and  the  levers  fall.  Feel  the 
tube ;  with  each  contraction  of  the  pump,  a  beat — the  pulse-beat— can  be 
felt. 

(d.)  Fix  and  study  the  tracing.  The  tracing  due  to  the  rise  of  the  lever 
next  the  pump  begins  sooner,  and  is  higher  than  the  one  from  the  lever  near 
the  outflow.  Make  two  ordinates  to  intersect  the  three  tracings,  one  where 
the  lower  pulse-curve  rises  from  the  abscissa,  and  the  other  where  the  u])per 
curve  begins.  Count  the  number  of  D.V.  of  the  tuning-fork  between  these 
lines.  Measure  the  length  of  the  tube  between  the  two  levers,  and  from 
these  data  it  is  easy  to  calculate  the  velocity  of  the  pulse- wave  in  feet  per 
second. 

3.  Scheme  of  the  Circulation. — Use  either  Rutherford's  scheme 
or  the  major  schema.  In  the  latter,  the  heart  is  represented  by 
an  elastic  pump  (Higginson's  syringe),  the  arteries  by  long  elastic 
tubes  dividing  into  four  smaller  tubes  with  clamps  on  them ;  two 
of  the  tubes  leading  into  tubes  filled  with  sponge  to  represent  the 
capillaries.  The  capillaries  lead  into  a  tube  with  thinner  walls 
representing  the  veins.  The  inflow  tube  into  the  heart  and  tlie 
outflow  tube  at  the  vein  are  placed  in  a  basin  of  water,  and  the 
whole  system  is  filled  with  water. 

(''/.)  IJse  two  mercury  manometers,  connect  one  with  the  arterial, 
and  the  other  with  the  venous  tube.  Adjust  a  float  on  each,  and 
cause  the  writing  points  of  the  two  floats  to  write  exactly  on« 
below  the  other  in  the  same  vertical  Hne  on  a  drum. 

(b.)  Unclamp  all  the  arteries,  and  work  the  pump,  regulating 
the  number  of  beats  by  means  of  a  metronome  beating  thirty  per 
minute,  and  compress  the  heart  to  the  same  extent  each  time  with 
a  lemon-squeezer.  Both  manometers  will  oscillate  nearly  to  the 
same  extent  with  each  beat.  Take  a  tracing  on  a  slow-moving 
drum. 

(c.)  Gradually  clamp  the  arteries  to  offer  resistance,  and  con- 
tinue to  pump  ;  the  pressure  in  the  arterial  manometer  will  rise 
more  and  more  with  each  beat  until  it  reaches  a  mean  level  with 
a  slight  oscillation  with  each  beat.  The  pressure  in  the  venous 
manometer  rises  much  less,  and  the  oscillations  are  very  slight  or 
absent. 

(d.)  While  the  mean  arterial  pressure  is  high,  cease  pumping; 
this  will  represent  the  arrest  of  the  heart's  action,  brought  about 
by  stimulation  of  the  peripheral  end  of  the  vagus;  the  arterial 
blood-pressure  falls  rapidly. 


298  PRACTICAL  PHYSIOLOGY.  [LXII. 

(e.)  Begin  pumping  again  until  the  mean  arterial  pressure  is 
restored,  and  then  unclamp  gradually  the  small  arteries.  The 
steady  fall  of  the  blood-pressure  represents  the  fall  obtained  when 
the  central  end  of  the  depressor  nerve  is  stimulated  (the  vagi 
being  divided). 

(/.)  Two  sphygmographs  may  be  adjusted  on  the  arterial  tube, 
one  near  the  heart  and  the  other  near  the  capillaries,  tracings 
being  taken  and  compared. 


ADDITIONAL  EXERCISES. 

4.  Rigid  and  Elastic  Tubes. — Arrange  an  experiment  as  shown  in  fig.  221. 
The  flask  should  at  least  hold  a  litre,  and  be  arranged  as  a  Marriotte's  flask. 
The  tubes — one  of  glass  and  the  other  of  caoutchouc— have  the  same  diameter, 
and  the  outflow  orifices  are  of  the  same  size.  The  glass  tube  is  attached  by  a 
short  elastic  tube  to  the  lead  tube  coming  from  the  reservoir.    As  the  fluid 


Fig.  221. — Marey's  Scheme  for  showing  that  in  the  Case  of  Rigid  and  Elastic  Tubes  of  the 
same  Calibre,  under  certain  Conditions,  the  Elastic  Tube  delivers  more  Fluid  than 
the  Rigid  one. 

flows  into  the  tubes,  they  are  compressed  rhythmically  to  imitate  the  inter- 
rupted beat  of  the  heart.  Observe  that  more  fluid  is  discharged  by  the  elastic 
than  by  the  rigid  tube. 

5.  The  Rheometer  (fig.  222)  is  used  to  measure  the  amount  of  blood 
flowing  through  a  vessel  in  a  given  time,  and,  therefore,  the  diameter  of  the 
vessel  being  known,  to  estimate  the  velocity  or  rate  of  blood-flow  through  an 
artery.  The  nozzles  of  the  instrument  are  inserted  and  tied  into  the  artery 
of  an  animal,  but  as  the  student  is  not  permitted  to  do  this,  use  an  India 
rubber  tube  to  represent  the  artery. 


LXII.] 


RIGID   AND   ELASTIC  TQBES. 


299 


(a.)  To  represent  the  heart — or  the  weight  of  a  column  ot  fluid— arrange 
a  Marriotte's  flayk  or  funnel  on  a  stand,  and  to  the  outflow  tube  attach  a 
narrow  india-rubber  tube,  and  clamp  it  after  tilling  it  with  normal  saline 
(to  represent  defibrinated  blood).  Fill  one  bulb  of  the  instrument  with 
deiibrinated  blood,  the  other  with  almond  oil,  and  close  the  top  of  the 
instrument  with  a  glass  plug. 

{b.)  Suppose  the  tube  to  represent  an  exposed 
artery  ;  about  the  middle  of  the  tube  apply  two 
ligatures  about  an  inch  apart  (or  two  clamps). 
Divide  the  part  of  the  tube  included  between  the 
two  ligatures,  and  tie  into  either  end  the  nozzles 
provided  with  the  instrument.  Call  the  one 
next  the  reservoir  or  heart  A,  and  the  other  one 
k.  Fix  the  instrument  into  the  nozzles,  the 
bulb  A  being  filled  with  oil  and  in  connection 
with  h,  B  with  defibrinated  blood  and  connected 
with  k.  The  instrument  is  fixed  in  position  by  a 
support  provided  with  it,  while  a  handle  which 
fits  into  two  tube-sockets  on  the  upper  surface  of 
the  disc  {e,  e^)  is  used  to  rotate  the  one  disc  on 
the  other. 

(c.)  All  being  now  ready,  take  the  clamp  off 
the  reservoir  of  blood  and  the  clamps  or  ligatures 
off  the  artery.  The  defibrinated  blood  flows  into 
the  bulb  A,  displaces  the  oil  in  it  towards  B, 
the  defibrinated  blood  of  B  being  forced  out  into 
the  artery  and  cauglit  in  a  suitable  vessel.  Of 
course,  in  the  animal  this  blood  simply  passes 
into  the  artery.  As  soon  as  the  bulb  A  is  filled 
with  blood,  which  is  indicated  by  a  mark  on 
the  glass,  the  disc  is  sucidenly  rotated  by  the 
hand,  whereby  B  communicates  with  A,  and  A 
with  k.  The  blood  now  flows  into  B,  displacing 
the  oil  in  it  into  A,  and  as  soon  as  this  takes 
j)lace,  the  disc  is  again  rotated.  This  process  is 
repeated  several  times.  Count  the  number.  The 
bulbs  have  the  same  capacity  and  are  exactly 
calibrated. 

The  time  is  most  conveniently  measured  by 
connecting  the  rheometer  with  an  electro -magnet 
registering  on  a  drum  each  rotation  of  the  disc, 
and  under  this  a  time-marker  records  seconds. 

Example. — Suppose  each  bulb  holds  5  cc,  and 
suppose  the  bulbs  to  be  filled  ten  times  with 
blood  during  100  seconds,  i.e.,  50  ccm.  flowed 
from  the  tube  in  i  second.  Sui)])Ose  the  diameter 
of  the  tube  to  be  2  mm.  {i.e.,  radius  =  i  mm.), 
this  would  give  a  sectional  area  of  3. 14  mm. 

The  velocity  (V)  is  calculated  by  the  ratio  of 
the  quantity  discharged  (Q)  to  the  sectional  area  (S),  i.e.,  the  quantity  of  fluid 
flowing  across  any  section  in  unit  of  time  -7-  area  of  that  section.     Hence — 

.5  cc,  or  what  is  the  same  thing,  500  cmm.,  are  discharged  in  one  second  ; 
therefore  the  velocity  is  •=  ■ — =  159  mm.,  or  about  six  inches  per  second. 


Fig.  222.— Rheometer. 


3CX)  PRACTICAL   PHYSIOLOGY.  [LXITI. 

6.  To  familiarise  himself  with  this  calculation,  the  student  would  do  well 
to  estimate  the  amount  of  water  discharged  from  a  tube  of  known  diameter. 
Let  the  tube  be  attached  to  a  litre-bottle  arranged  as  a  Marriotte's  flask. 
Estimate  the  amount  of  fluid  discharged  in  a  given  time,  and  from  this 
calculate  the  velocity  of  the  flow  in  the  tube. 


LESSON  LXIII. 


CAPILLARY  BLOOD-PRESSURE— LYMPH-HEARTS 
—BLOOD-PRESSURE  AND  KYMOGRAPH. 

1.  Blood-Pressure  in  the  Capillaries. 

•  (a.)  Make  the  following  apparatus  (fig.  223),  consisting  of  a  disc 
of  glass,  2  cm.  long,  3  to  4  mm.  broad,  and  i  mm.  thick,  and  on  its 
under  surface  fix  with  cement  a  glass  plate  (a),  with  a  surface  of 
5  mm.  square.  Two  threads  supporting  a  paper  scale-pan  are 
attached  to  tlie  glass  disc.  Arrange  the  glass  plate  {a)  over  the 
skin  on  the  dorsal  surface  of  tlie  middle  finger,  just  at  the  root  of 
the  nail.  Add  weights  to  the  scale-pan  until  the  skin  becomes  pale, 
^ote  the  weight  necessary  to  bring  this  about,  hut  observe  that  the 
skin  does  not  become  pale  all  at  once. 

{h.)  Test  how  altering  the  position  of  the  Jaand  affects  the  pressure 
in  the  capillaries. 

2.  Destroy  the  brain  of  a  frog.  Very  slightly  curarise  it. 
Examine  microscopically  the  circulation  in  the  web  of  its  foot  and 
in  its  mesenteric  vessels. 

Apply  a  drop  of  croton  oil  or  mustard  for  a  minute  or  less. 
Observe  the  inflammation  thereby  produced,  and  the  changes  in 
the  appearance  of  the  blood-vessels  and  the  blood-flow,  until  the 
latter  is  finally  arrested  in  a  condition  of  stasis,  and  exudation  takes 
place. 

3.  Posterior  Lymph-Hearts. 

(rt.)  Destroy  the  brain  of  a  frog,  place  it  on  its  belly,  and  watch 
the  beating  of  the  posterior  pair  of  lymph-hearts,  which  are 
situated  one  on  each  side  of  the  urostyle  in  the  triangle  between 
coccygeo-iliacus  (?'c),  gluteus  (^/),  origin  of  the  vastus  externus  {ve) 
and  pyramidaHs  (/>)  muscles  (fig.  224). 

{h.)  Remove  the  skin  covering  them,  taking  care  not  to  cut  too 
far  outwards,  else  a  cutaneous  vein  will  be  injured  and  bleed  freely. 
Count  the  number  of  beats  per  minute,  noting  that  the  rhythm  \b 


LXIII.] 


CAPILLARY   BLOOD-PRESSURE. 


301 


not  synchronous  with  the  blood-heart,  whose  movements  can 
usually  be  distinguished  without  opening  the  chest. 

(c.)  Destroy  the  posterior  part  of  the  spinal  cord  with  a  seeker 
or  wire,  and  observe  that  the  rhythmical  automatic  movements  of 
the  lymph-hearts  cease. 

4.  Estimation  of  the  Blood-Pressure  by  Ludwig's  Kymograph. 

— As  students  are  not  permitted  to  perform  experiments  upon  live 
animals,  the  most  they  can  do  in  this  experiment  is  to  arrange  the 
necessary  apparatus  as  for  an  experiment,  and  to  make  the  necessary 
dissection  on  a  dead  animal. 


Fig.  223.  —  Apparatus 
used  by  V,  Kries 
for  Estimating  the 
Capillary  Blood- 

Piessure. 


FlO.  224.— Posterior  Pair  of  Lymph-Hearts  {L) 
of  the  Frog. 


A.  (//.)  Arrange  the  recording  apparatus  for  a  continuous  tracing.  The 
clockwork  is  wound  up,  and  the  drum  is  so  adjusted  that,  when  it  moves,  it 
unwinds  the  continuous  white  paper  from  a  brass  bobbin  placed  near  it. 
Arrange  a  time-marker  connected  with  a  clock,  provided  with  an  electric 
interrupter,  to  mark  seconds  at  the  lower  part  of  the  paper.  It  is  usual  to 
use  a  ])en-writer  charged  with  a  solution  of  aniline  (red  or  blue),  to  which  a 
little  glycerin  is  added  to  make  it  flow  freely. 

{b.)  Partially  fill  the  manometer  with  dry  clean  mercury,  and  in  the  open 
limb  of  the  manometer  place  the  float,  provided  with  a  pen  or  sable  brush 
moistened  with  aniline  ink  containing  a  little  glycerin.  See  that  the  float 
rests  on  the  convex  surface  of  the  mercury  (fig.  225). 

(f. )  The  closed  or  proximal  side  of  the  manometer  at  its  upper  part  is  like 
a  T-tube,  the  stem  of  Avhich  is  connected  by  thick  india-rubber  tubing  to  a 
piece  of  flexible  lead  tubing ;  on  the  free  end  of  the  latter  is  tied  a  glass 
cannula  of  considerable  size,  and  over  the  india-rubber  tubing  connecting 
the  cannula  with  the  lead  tube  is  placed  a  clamp.     The  proximal  end  of  the 


302 


PRACTICAL   PHYSIOLOGY. 


[lxiil 


manometer  is  filled  by  means  of  a  syringe  with  a  saturated  solution  of  sodium 
carbonate  as  high  as  the  stem  of  the  T-piece.  To  it  is  attached  a  long  india- 
rubber  tube,  which  is  connected  with  a  ])ressure- bottle  filled  with  a  saturated 
solution  of  sodium  carbonate,  and  kept  in  position  by  a  cord  passing  over  a 
pulley  fixed  in  the  roof.  A  clamp  compresses  the  india-rubber  tube  just 
above  the  manometer.  Open  this  clamp  and  also  the  one  at  the  end  of  the 
lead  pipe.     The  alkaline  solution  fills  the  whole  system,  and  after  it  does 

so,  and  no  air-bubbles  are  present, 
close  the  clamp  at  the  end  of  the 
lead  tube,  and  then  the  one  on  the 
pressure-bottle  tube.  It  is  well  to 
have  an  inch  or  more  of  positive 
pressure  in  the  manometer.  See 
that  the  writing-style  writes  smooth- 
ly on  the  paper,  and  that  it  is  kept 
in  contact  with  the  latter  by  a  silk 
thread  with  a  shot  attached  to  its 
lower  end. 

B.  Insert  the  Cannula. — (a.) 
Arrange  the  necessary  insfruvients 
in  order  on  a  tray — scissors,  scalpels, 
forceps  (coarse  and  fine),  seeker, 
well-waxed  ligatures,  small  aneurism 
needle,  bull-dog  forceps,  cannula, 
sponges. 

{b.)  Make  the  necessary  dissection 
on  a  dead  rabbit.  Fix  the  rabbit 
in  a  Czermak's  holder,  as  would  be 
done  if  the  animal  were  alive.  Clip 
away  with  a  pair  of  scissors  the  hair 
over  the  neck,  and  with  a  moist 
sponge  moisten  the  skin  to  prevent 
any  loose  hair  from  flying  about. 
Pinch  up  the  skin  on  one  side  of  the 
trachea,  between  the  Isft  thumb  and 
forefinger,  and  divide  it  with  a 
sharp  scalpel.  This  exposes  the 
fascia,  which  is  then  torn  through 
with  forceps  ;  draw  the  sterno- 
mastoid  aside,  and  gently  separate 
the  muscles  with  a  ".seeker"  until 
the  carotid,  accompanied  by  the 
vagus,  depressor,  and  sympathetic 
nerves,  is  seen.  The  dissection  is 
made  beloAv  the  level  of  the  larynx. 
Lying  just  external  to  the  carotid 
is  the  vagus.  After  raising  the  carotid,  under  it,  and  internal  to  the  vagus, 
are  seen  two  fine  nerves  ;  the  more  internal  and  finer  one  is  the  depressor 
or  superior  cardiac  branch  of  the  vagus  (fig.  226),  the  other  is  the  sjonpathetic. 
Note  that  the  smallest  of  the  three  nerves  is  the  depressor,  which  is  easily 
isolated  from  the  sym}»athetic  by  means  of  a  seeker.  If  in  doubt,  trace 
the  sympathetic  u]Avards  until  it  merges  into  the  large  swelling  of  the 
superior  cervical  sympathetic  ganglion.  The  depressor  should  be  tied  low 
down  in  the  neck  and  divided  below  the  ligature,  as  if  for  an  experiment  on 
its  function.  It  is  an  afferent  nerve,  and  therefore  its  central  end  must  be 
■timulated. 


FlO.  225. — Simple  Form  of  Kymograph.  On 
the  right  is  the  manometer,  the  float  re- 
cording the  movements  of  the  mercury  on 
a  simple  revolving  cylinder. 


LXIII.] 


CAPILLARY  BLOOD-PRESSURE. 


303 


The  vagus  should  also  be  isolated  and  ligatured  as  if  for  experiment.  It  is 
well  to  use  shielded  electrodes,  such  as  are  shown  in  fig.  227,  The  vagus  ia 
tied  and  divided,  and  if  its  peripheral 
end  is  to  be  stimulated,  the  peri- 
pheral end  is  drawn  through  the 
shielded  electrodes,  which  are  then 
connected  with  the  secondary  coil  of 
an  induction  machine.  To  complete 
the  arrangements,  an  induction 
machine  ought  to  be  set  up. 

(c.)  Open  the  sheath,  and  with  the 
seeker  carefully  isolate  about  an  inch 
of  the  carotid.  Pass  a  ligature  under 
the  artery  by  means  of  a  fine  aneurism 
needle,  withdraw  the  needle,  and 
ligature  the  artery.  About  an  inch 
on  the  cardiac  side  of  the  latter, 
clamp  the  artery  with  bull-dog 
forceps.  Raising  the  artery  slightly 
by  the  ligature,  with  a  fine-pointed 
pair  of  scissors  make  an  oblique 
V-shaped  slit  in  the  artery,  and  into 
it  intrt)duce  a  suitable  glass  cannula 
with  a  short  piece  of  india-rubber 
tubing  tied  on  to  it.  Place  another 
ligature  round  the  arterv,  and  tie  it 
round  the  artery  and  over  the 
shoulder  of  the  cannula.  The  point 
of  the  cannula  is  of  course  directed 
towards  the  heart.  Fill  the  cannula 
with  the  soda  solution,  and  into  the 
cannula  slip  the  glass  nozzle  at  the 
end  of  the  lead  pipe,  tying  it  in 
securely.  Unscrew  the  clamp  at  the 
end  of  the  elastic  tubing.  Set  the 
clockwork  going  ;  if  one  were  operating  on  a  living  animal,  the  next  thing  to 
do  would  be  to  remove  the  clamp  or  forceps  between  the  cannula  in  the 
artery  and  the  heart.  At  once  tlie  swimmer  would  begin  to  move  and  record 
its  oscillations  on  the  paper  moving  in 
front  of  it. 

{d.)  Before  joining  the  lead  tube  to 
the  cannula,  isolate  the  vagus,  the 
largest  of  the  three  nerves  ;  put  a  liga- 
ture round  it,  and  divide  it  above  the 
ligature.  Isolate  also  the  depressor 
nerve,  put  a  ligature  round  it  low  down 
in  the  neck,  and  divide  it  between  the 
ligature  and  the  heart.  The  latter  is 
easily  distinguished  ft'om  the  sympa- 
thetic, as  it  is  the  smallest  of  the  three 
nerves  accompanying  the  carotid.  In 
the  dead  rabbit  the  depressor  may  be 
traced  up  to  its  origin  by  two  branches, 
one  from  the  vagus,  and  the  other  from  the  superior  laryngeal  (fig.  226). 
Moreover,  if  the  sympathetic  be  traced  upwards,  a  ganglion  will  be  found  on 
it.     This  is  merely  to  be  regarded  as  an  exercise  for  practice. 


Fig.  226.— Nerves  In  the  Neck  of  the  Rabbit. 
a.  Sympathetic ;  6.  Hypoglossal,  with  c, 
its  descending  branch  (descendens  noni) ; 

d.  Branch  of  a  cervical  nerve  joining  e ; 

e.  Vagus,  with  /,  its  superior  laryngeal 
branch ;  g  and  h.  The  origins  of  the  supe- 
rior cardiac  or  depressor  nerve. 


\asL?sy 


Fig.  227.— Forms  of  Shielded  Electrode! 
for  Stimulating  the  Vagus  or  a  Deeply- 
Seated  Nerve. 


304 


PRACTICAL  PHYSIOLOGY. 


[Lxni. 


{e. )  In  every  case  a  base  line  or  line  oi  no  pressure  must  be  recorded  on  the 
wntinuous  paper.  This  indicates  the  abscissa,  or  when  the  mercury  is  at  tha 
same  height  in  the  two  limbs  of  the  manometer. 

(/'.)  Measure  a  Blood-Pressure  Tracing.— Lay  the  tracing  on  a 
table.  Take  a  right-angled  triangle  made  of  glass  or  wood,  and 
place  one  of  the  sides  bounding  its  right  angle  upon  the  abscissa, 
the  other  side  at  right  angles  to  this  has  engraved  on  it  a  millimetre 
scale.  Or  use  a  millimetre  scale  as  in  fig.  228.  Read  off  the  height 
in  millimetres  from  the  base  line  to  the  lowest  point  in  the  curve 


Fio.  228.— Blood-Pressure  Tracing  of  the  Carotid  of  a  Dog,  taken  with  lAdwlg'a 

Mercurial  Manometer. 


and  also  to  its  highest  point;  take  the  mean  of  the  two,  and 
nmltiply  by  tico,  this  will  give  the  mean  arterial  pressure.  Instead 
of  measuring  only  two  ordinates,  measure  several,  and  take  the 
mean  of  the  number  of  measurements.  In  all  cases  the  result  has 
to  be  multiplied  by  two. 

{y.)  Measure  the  blood-pressure  tracing  (fig.  229)  of  the  carotid 
of  a  dog  from  the  base  line  T.  It  represents  the  effect  of  stimula- 
tion of  the  vagus,  and  the  arrest  of  the  heart-beat,  and  the  con- 
sequent great  faU  of  the  blood-pressure. 


LXni.]  CAPILLARY   BLOOD-PRESSURE.  305 

(h.)  In  every  kymograph  tracing,  notice  the  smaller  undulations 
due,  each  one,  to  a  single  beat  of  the  heart,  and  the  larger  ones  due 
to  the  respiratory  movements  (fig.  229).  In  a  blood-pressure  trac- 
ing taken  from  a  dog  with  the  vagi  not  divided,  observe  that  tlie 
size  of  the  heart-beats  on  the  descent  of  the  respiratory  wave  is 
greater,  while  the  number  of  beats  is  less  than  on  the  ascent. 

(i.)  Study  blood-pressure  tracings  obtained  by  stimulation  of 

(i.)  The  peripheral  end  of  tlie  vagus  (fig.  229). 
(ii.)  The  central  end  of  the  depressor, 
(iii.)  The  central  end  of  a  sensory  nerve. 


FlO.  229.— 5. p.  Blood-pressure  tracing  of  dog's  carotid,  stimulation  of  the  vagus  at 
the  indent  in  the  line  S ;  T  indicates  time  in  seconds,  and  is  the  abscissa. 

6.  Make  a  Glass  Cannula. —Heat  in  the  flame  of  a  blowpipe  a  piece  of  hard 
glass  tubing  about  5  mm.  in  diameter.  When  it  is  soft,  take  it  out  of  the 
flame,  draw  it  out  gently  for  about  3  cm.  Allow  it  to  cool  ;  make  the  gas-jet 
smaller,  heat  the  thin  drawn-out  part  of  the  tube,  and  draw  it  out  very  slightly. 
This  makes  a  shoulder.  With  a  triangular  file  just  scratch  the  narrow  part 
obliquely  beyond  the  second  constricted  part,  and  break  it  off.  A  cannula 
with  a  shoulder  and  an  oblique  narrow  orifice  is  thus  obtained.  Round  off"  the 
oblique  edges  either  by  a  file,  rubbing  them  on  a  whetstone,  or  heating  slightly 
in  a  gas-flame.  Tie  a  piece  of  india-rubber  on  the  other  end,  and  the  cannula 
is  com[)lete.  Instead  of  a  straight  glass  cannula  with  a  shoulder,  the  form 
shown  in  fig.  230  may  be  used.  It  has  a  lateral  tube,  which  is  closed  by  means 
of  a  caoutchouc  tube,  and  is  useful  in  this  respect,  that  the  large  bulb  prevents 
clotting  of  the  blood,  while  if  clotting  does  occur,  the  clot  can  readily  be 
washed  out  by  means  of  the  pressure  bottle  through  the  lateral  tube. 

6.  Effect  of  Vagus  on  Heart. — The  student  is  not  permitted  to  do  this 
experiment  on  a  living  animal      It  can,  however,  bo  shown  on  a  rabbit  or  cat 

U 


3o6 


PRACTICAL  PHYSIOLOGY. 


[lxiv. 


just  killed.     Expose  the  vagus  rapidly,  open  the  chest  and  observe  the  heart 
beating,  or  thrust  a  long  needle  through  the  unopened  chest  in  the  heart,  then 

on  stimulating  the  peripheral 
end  of  the  vagus  with  an  inter- 
rupted current  the  movements 
of  the  heart  are  arrested  for  a 
short  time — the  heart  itself 
being  in  diastole. 

7.  Effect  of  Swallowing  on 
the  Heart  (p.  312). 

8.  B.  P.  in  Man  v.  Baach's 
Sphygmomanometer.  —  Tliis 
consists  of  a  brass  capsule 
covered  on  its  open  end  with 
sheets  of  caoutchouc,  and  con- 
nected by  means  of  a  tube 
with  a  manometer  constructed 
on  the  principle  of  an  aneroid 
barometer.  It  is  best  to 
apply  it  to  the  superficial 
temporal  artery,  as  there  is  a 
bony    supj)ort    behind     that. 

One  compresses  the  artery  until  the  pulse  beyond  is  obliterated,  and  then 
reads  off  directly  the  pressure  required  to  do  this. 


FlO.  230— Improved  Form  of  Arterial  Cannula,  by 
frail  Qois-Frank.  A  is  tied  into  the  artery  ;  B  is 
attached  to  the  lead  tube  of  the  manometer : 
and  C,  the  lateral  tube,  is  closed  with  an  elastic 
(damped)  tube. 


LESSON  LXIV. 
PERFUSION  THROUGH  BLOOD-VESSELS. 

Perfusion  through  Blood- Vessels. — By  perfusing  fluids  through 
the  blood-vessels  of  the  body  as  a  whole,  or  by  perfusing  blood 
or  other  fluids  through  isolated  "  surviving  "  organs,  much  may  be 
learned  regarding  the  action  of  drugs  and  other  conditions  on 
the  blood-vessels.  The  blood-vessels  of  the  frog  and  tortoise,  the 
excised  kidney,  and  other  organs  have  been  used  for  this  purpose. 

Perfusion  through  Blood-Vessels  of  Frog. 

(a.)  Pith  a  frog,  expose  its  heart,  snip  one  aorta,  and  allow  the 
blood  to  flow  out.  Previously  a  fine  glass  cannula  with  a  shoulder 
on  it  must  have  been  prepared.  Tie  the  cannula  into  one  aorta, 
and  let  the  hgature  also  include  the  other  aorta. 

(b.)  Attach  the  cannula  to  an  india-rubber  tube  containing  normal 
sahne  and  connected  with  a  glass  funnel  filled  with  normal  saline 
and  held  in  a  suitable  holder,  e.r/.,  a  ring  on  a  retort  stand,  placed 
about  6-7  inches  above  the  heart.  See  that  there  is  no  air  in  the 
connections,  and  that  the  cannula  is  filled  with  normal  saline  by 
means  of  a  fine  pipette  before  it  is  connected  up  with  the  pressure 
tube.     Put  a  cHp  on  the  pressure  tube. 


LXIV.] 


PERFUSION   THROUGH   BLOOD-VESSELS. 


307 


(c.)  Make  a  snip  in  the  sinus  venosus  or  venae  cavse  to  let  the 
fluid  run  out.  Hang  up  the  frog  on  a  suitable  holder.  Take  the 
clip  off  the  pressure  tube,  allow  the  normal  saline,  or  Ringer's  fluid, 
to  run  into  the  blood-vessels  and  to  wash  out  all  the  blood,  until 
the  saline  runs  clear  from  the  veins.  Collect  the  outflow  in  a 
funnel  which  is  placed  in  a  graduated  measure. 

(d.)  After  the  Ringer's  fluid  runs  clear,  collect,  measure,  and 
record  the  amount,  when  it  is  constant,  every  five  minutes. 

(e.)  Substitute  normal  saline  or  Ringer's  fluid,  to  which  some 
drug  has  been  added,  and  perfuse  it.  Note  the  effect.  If  there  is 
an  increased  outflow,  the  blood-vessels,  chiefly  the  arterioles,  have 
been  dilated.  If  less,  they  have  been  contracted.  Record  the 
results,  and  if  necessary  make  a  chart  to  show  the  result. 

The  water-tortoise  is  a  very  convenient  animal  to  use,  the  perfusion  cannula 
being  fixed  in  the  third  or  fourth  aorta,  the  others  being  tied.  It  is  con- 
veniently placed  in  a  glass  hmnel  when  perfusion  is  being  carried  on. 

In  the  frog,  after  a  time,  there  is  considerable  a'dema  of  the  lymph-sacs. 

It  is  most  important  that  the  student  should  keep  notes  of  his  results.  From 
the  results  obtained,  plot  a  curve  on  paper  divided  into  squares.  Make  the  base 
line  represent  time,  and  the  vertical  lines,  or  ordinates,  the  amount  of  outllow. 

Some  substances  greatly    contrad  the   blood-vessels,   e.g.,   very 

dilute  nitric  acid,  and   extract   of   the  suprarenal  capsules.     The 

latter  is  specially  powerful  in  constricting  the  arterioles.     (Schdfer 

^  Oliver.)     Others  dilatn  the  vessels,  especially  the  nitrites,  xTnTTT- 

Perfusion  Experiments. 


Water-Tortoise.    Fluid  been 

Water-Tortoise 

.    Fluid  been 

Frog.    Fluid  been 

running 

60'.     Pressure, 

running  60'. 

Pressure, 

running  20'.    Pressure, 

7 

inches. 

7  inches. 

7  inches. 

Time. 

Amount  of  Out- 
flow in  c.c. 

Time. 

Amount  of  Out- 
flow in  c.c. 

T!r«i»         Amount  of  Out 
^'™®-             flow  in  C.C. 

I.O 

=         °  ^t^ 

■^■5  (3.0 

= 

'^    I     • 

2.50           =           14-5^  -3  V 

1. 10 

=     "   ll.s 

"  2    (3*io 

= 

\\\a 

2-55           =          15-5  I  S.£ 

i-iS 

^5     f  c^ 

= 

3-0             =           15-5  (  els 

1.20 

=        IS  )  -'^ 

■ 

f3-i5 

= 

8    > 

g 

3-IO           =           15.5^1   c  " 

1-25 

=            "      )0"c 

3- 20 

= 

8 

-5 

3.15  suprarenal  extract. 1 

1.30 

7    Y'^'^ 

325 

= 

8 

3.20          =           2.5 

1-35 

7    )  W   "" 

330 

= 

8 

^1 

3.25          =           2.0 

1.40 

6.5\   ^ 

3-35 

= 

8 
^0    i 

3.30         =           2.0 

1-45 

5-5     = 

3-40 

= 

U^ 

3.35                     ceasetl. 

1.50 

4-5     13 

3-45 

= 

18 

1-55 

4-5  1;: 

rri 

3- 50 

= 

^^ 

■^--i 

2.0 

2-5 

5(2 

6.5      g 

1 

3-55 
4.0 

= 

24    ) 
22    ^ 
22 

1-a^ 

2.10 

=           5-5      2 

1- 

4-5 

= 

. 

1  Made      by     Messrs 

».iS 

5    J  "" 

« 

4.10 

= 

21 

.9 

Willows,      Francis      & 

73 

4-15 

= 

19 

rt 

Butler,    chemists,    Hol- 

4.20 

= 

17 

CO 

boru,  London. 

8 

4.25 

= 

14 

4.30 

= 

12.5 

4.35 

= 

II 

§ 

4.40 

= 

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4-45 

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p^ 

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10    )    ga 

3o8 


PRACTICAL  PHYSIOLOQY. 


[LXV. 


PHYSIOLOGY  OF  RESPIRATIOW. 


LESSON  LXV. 

MOVEMENTS     OP     THE     CHEST     WALL  — ELAS- 
TICITY OP  LUNGS— HYDROSTATIC  TEST. 

1.  Movements  of  the  Chest  Walls — Stethograph. 

A  Rabbit. — (a.)  Arrange  a  drum  and  time-marker.  Fix  a  rabbit 
conveniently,  e.g.,  on  Czermak's  rabbit-holder,  or  use  the  simpler 
form  of  Malaysez  or  Steinach,  and  with  tapes  tie  on  its  chest  Marey's 
double  tambour  (fig.  231),  connecting  the  latter  with  a  recording 


FWb  a3i. — Marey's  Double  Tambour,  to  be  tied  round  the  chest  of  a  rabbit. 

tambour  adjusted  to  write  on  the  drum.  Introduce  between  the 
receiving  and  recording  tambours  either  the  valve  usually  suppUed 
with  Marey's  apparatus  or  a  T-tube  vdth.  a  screw  clamp,  whereby 
the  pressure  within  the  system  of  tubes  can  be  regulated.  Take 
a  tracing.     If  one  of  the  receiving  tambours  be  placed  over  the 


LXV.] 


MOVEMENTS    OF  THE   CHEST  WALL. 


309 


cardiac  impulse,  the  tracing  will  show  also  the  number  of  beats  of 
the  heart  (fig.  232). 

B.  Man. — (6.)     Stethograph     (Marey's). — Cause    a    person    to 
expose  his  chest.     Raise  the  screw  ((/)  of  the  stethograph,  and  fix 


Fig.  232.— Stethograph  Tracing  of  a  Rabbit.    The  tracing  shows  undulations  due  to 
the  beats  of  the  heart.    T  indicates  time  in  seconds. 

the  plate  (/)  of  the  instrument  on  the  exposed  chest,  with  tapes 
attached  to  c  and  d.  Depress  g,  connect  the  tube  (a)  with  a 
recording  tambour,  with  the  same  precautions  as  in  1,  A.,  and 
take  a  tracing  (fig.  234).  Examine  the  tracing,  noting  the  relation 
between  inspiration  and  expiration. 

(c.)  Polygraph  (Eothe). — Use  the  polygraph   of  Rothe,  record 


Fio.  233.— Mareys  Stethograph, 

the  respiratory  movements  by  means  of  the  bag  (fig.  2p8,  A),  and 
study  the  tracing  (fig.  234). 

2.  Elasticity  of  the  Lungs. 

Remove    the   whole   of   the   front   of   the   chest   in  the  rabbit 
already   used.     Observe    the    collapsed   lungs.     To   the    tracheal 


310  PRACTICAL  PHYSIOLOGY.  [LXV. 

cannula  attach  an  india-rubber  bag  such  as  is  used  with  a  spray- 
producer,  and  inflate  the  Umgs.  Cease  to  pump  air  into  the  lungs, 
and  observe  how  they  collapse. 

3.  Hydrostatic  Test. 

Cut  out  the  lungs  and  the  heart.  Place  them  in  a  vessel 
of  water.  The  whole  will  float,  as  the  lungs  contain  so  much  air. 
Cut  ofl"  a  small  piece  of  one  lung,  throw  it  into  water,  it  floats. 
This  is  the  hydrostatic  test.  Compare  a  piece  of  pneumonic  lung ; 
the  latter  sinks. 

4.  Apnoea. — Count  the  number  of  your  own  respirations  per 
minute.  Take  a  series  of  rapid  inspirations.  Isote  that  several 
seconds  elapse  before  the  next  insniration.  This  is  the  period  of 
apnoea. 


Fia.  234.— Stethograph  Tracing,  taken  with  Rotlie'a  Polygraph. 

5.  Deglutition  Apnoea. 

(a.)  Test  how  long  you  can  "hold  your  breath."  Note  the 
time. 

(b.)  After  a  time,  sip  water  without  breathing,  and  note  that, 
under  this  condition,  the  time  the  breath  can  be  held  is  nearly 
doubled.  The  successive  acts  of  deglutition  influence  the  respira- 
tory centre  in  the  medulla  oblongata,  as  well  as  the  cardio-inliibitory 
centre  {Kronecker).  The  latter  is  referred  to  at  p.  312.  Other 
centres  are  influenced  by  sipping. 

6.  Voluntary  Respiration. — Test  in  yourself  how  long  this  can 
be  kept  up.  As  a  rule,  one  cannot  continue  it  for  more  than  two 
minutes. 

7.  Stethometer  of  Burdon-Sanderson. 

(a.)  Prepare  a  drum  and  time-marker  as  in  the  previous  experiments. 
Cause  a  person  to  expose  his  chest,  and  seat  himself  conveniently.  The  instru- 
ment is  suspended  by  a  broad  band  placed  round  the  neck,  the  horizontal  bar 
being  behind  the  body. 

(h.)  The  most  important  diameters  of  the  chest  to  measure  are— "Those 
connecting  the  eighth  rib  in  the  axillary  line  with  the  same  rib  on  the  oppo- 


LXVI.]  VITAL  CAPACITY,   ETC.  3II 

site  side,  the  manubrium  sterni  with  the  third  dorsal  spine,  the  lower  end  of 
the  sternum  with  the  eighth  dorsal  spine,  and  the  ensiform  cartilage  with  the 
tenth  dorsal  spine."  Measure  oiily  the  first.  Adjust  the  knob  of  the  tambour 
on  one  side  against  the  eighth  rib,  as  above,  while  the  movable  bar  with  its 
knob  is  placed  against  the  opposite  corresponding  rib.  Connect  the  tambour 
with  the  recording  tambour,  introducing  a  j-piece,  the  stem  of  which  is 
provided  with  an  india-rubber  bag  and  screw  clamp  to  regulate  the  pressure 
within  the  air-system. 

8.  Intra-Thoracic  Pressure.— For  practice  this  can  be  done  on  a  dead 
rabbit. 

(a.)  Fix  the  dead  rabbit  in  Czermak's  rabbit-holder.  Expose  the  trachea, 
tie  into  it  a  knee-shaped  glass  cannula.  Make  a  small  water-manometer  or 
bent  U-tube  with  a  millimetre  scale  attached,  fill  it  about  half  full  with 
coloured  water,  and  to  the  proximal  limb  attach  an  india-rubber  tube  with  a 
T-j)iece  and  screw  clamp,  as  in  other  experiments.  Connect  the  tracheal 
cannula  with  the  manometer  tube,  tighten  the  screw  clam]),  and  see  that  the 
water  stands  at  the  same  level  in  both  limbs  of  the  manometer. 

(Ik)  Open  both  pleurae  without  injuring  the  lungs.  The  lungs  collapse  and 
the  water  is  depressed  in  the  proximal  side  of  the  manometer,  and  rises  in  the 
open  limb. 

9.  Respiratory  Movements  of  Frog; — In  the  frog  the  air  is  forced  into  the 
lungs. 

(a.)  Observe  rhythmical  movements  of  the  muscles  of  the  floor  of  the  mouth 
and  of  the  muscles  attached  to  the  hyoid  bone,  the  cavity  of  the  mouth  is 
thus  diminished.     Coincident  with  these  are 

{b.)  ^lovements  resulting  in  closure  of  the  external  nares,  and  thus  the  air 
is  forced  into  the  lungs.  At  the  same  time,  the  glottis  is  opened,  but  the 
mouth  must  be  o})ened  to  see  this. 

{c. )  The  act  of  expiration  is  performed  by  movements  of  the  muscles  of  the 
flanks  compressing  the  visceral  contents. 


LESSON  LXVI. 


VITAL  CAPACITY  —  EXPIRED  AIR  —  PLEURAL 
PRESSURE— GASES  OP  BLOOD  AND  AIR. 

1.  Vital  Capacity. — Estimate  this  on  Hutchinson's  spirometer, 
i.e.,  take  the  deepest  possible  inspiration,  and  then  make  the  deepest 
possible  expiration,  expiring  into  the  mouthpiece  of  the  spirometer. 
The  average  vital  capacity  is  about  3700  cc.  (230  cubic  inches),  but 
it  varies  with  age,  height,  sex,  and  practice  in  using  the  instru- 
ment, &c. 

2.  Changes  in  Expired  Air. 

(a.)  Black's  Experiment. — Place  equal  quantities  of  lime-water 
in  two  vessels  (A  and  B).  Take  a  deep  breath,  close  the  nostrils, 
and  expire  through  a  bent  glass  tube  into  A.     The  lime-water  soon 


312 


PRACTICAL  PHYSIOLOGY. 


[LXVi. 


becomes  milky,  owing  to  the  large  amount  of  carbonic  acid  expired 
combining  with  the  lime  to  form  carbonate  of  lime.  With  the 
elastic  pump  of  a  spray-producer  pump  the  air  of  the  room  through 
B.  B  remains  clear  and  does  not  become  turbid.  Therefore  the 
carbonic  acid  must  have  been  added  to  the  inspired  air  in  the 
respiratory  organs, 

(ft.)  Miiller's  Valves. — Arrange  two  flasks  (A  and  B)  and  tubes  as  in  fig.  235 
with  some  lime  water  in  both.  Close  the  nostrils,  apply  the  mouth  to  the 
tube,  and  inspire.     The  air  passes  in  through  A,  and  is  freed  of  any  CO.2  it 

may  contain.  Expire,  and  tlie  air 
goes  out  through  B,  in  which  the 
lime-water  becomes  turbid. 

(c.)  Haywood's  Experiment. — 
Place  about  two  litres  of  water 
in  a  basin,  and  in  it  put  erect 
a  bell  -  jar.  Ascertain  that  a 
lighted  taper  burns  in  the  jar. 
Renew  the  air,  place  in  the  neck 
of  the  jar  a  glass  tube  with 
a  piece  of  india-rubber  tubing 
attached.  Close  the  nostrils,  apply 
the  mouth  to  the  tube,  and  inspire. 
The  water  rises  in  the  bell-jar.  Then  expire,  the  water  sinks,  and  the  air 
which  was  originally  present  above  the  water  has  been  taken  into  and 
expelled  again  from  the  respiratory  ])assages.  Remove  the  cork,  and  place 
a  lighted  taper  in  the  expired  air.     The  taper  is  extinguished  (fig.  236). 

3.  Swallowing. — Test  on  yourself  how  rapidly  (few  seconds) 
you  can  swallow  a  large  glass  of  water.  In  swallowing  Uquids,  the 
Hquid  is  projected  through  the  pharynx  and  oesophagus  right  into 
the  stomach  chiefly  by  the  contraction  of  the  mylohyoid  muscles  in 
the  floor  of  the  mouth  {Kronecker  and  Meltzer). 


Fig.  235.-^1111161^3  Valves. 


ADDITIONAL  EXERCISES. 

4.  Pressure  within  the  Pleura. — Fix  one  end  of  a  caoutchouc  tube  to  a 
water-manometer  (water  coloured  red),  and  the  other  end  to  a  trocar  and 
cannula.  Thrust  the  trocar  obliquely  through  an  intercostal  space  until  the 
]»oint  of  the  trocar  lies  in  the  space  between  the  two  layers  of  the  pleura. 
Observe  how  the  level  of  the  water  rises  in  the  proximal  limb  of  the  mano- 
meter, indicating  the  negative  pressure  in  the  pleural  cavity. 

,5.  Blood  Grases.— Blood  yields  about  sixty  volumes  per  cent,  of  gases  to  a 
vacuum.  The  gases  in  the  blood — COo,  0,  and  N — are  extracted  from  it  by 
means  of  a  gas-pump.  Various  forms  have  been  constructed,  including  those 
of  Ludwig,  Pfliiger,  and  Alvergniat.  Study  these  various  forms  and  the 
principle  of  their  construction.  It  requires  a  considerable  amount  of  time  to 
become  thoroughly  acquainted  with  the  practical  working  of  these  instruments 
but  this  is  not  necessary  from  a  student's  point  of  view. 


lxvl] 


VITAL  CAPACITY,   ETC. 


313 


(a.)  Suppose  the  gases  of  the  blood  to  be  extracted  ;  they  are  collected  in  a 
eudiometer  over -mercury  (fig.  237).  Or,  for  practice,  and  merely  to  grasp  the 
principle  how  the  relative  proportion  of  the  gases  in  a  mixture  is  ascertained, 
the  student  may  use  air  containing  a  small  quantity  of  carbon  dioxide. 

{b.)  Fuse  a  ball  of  potash  on  the  end  of  platinum  wire  (best  done  in  a  bullet- 
mould).  Introduce  this  under  the  mercury  into  the  gases  in  the  eudiometer. 
The  caustic  potash  absorbs  all  the  CO2  (twenty-four  hours),  and  the  diminution 
in  volume  represents  the  proportion  of  COg  in  the  mixture. 

(o.)  With  a  curved  pipette  introduce  a  solution  of  pyrogallic  acid  into  the 
eudiometer  containing  the  remainder  of  the  gases  ;  this  unites  with  the  potash 
to  form  pyrogallate  of  potash,  which  rapidly  absorbs  the  oxygen.  Tlie  decrease 
in  volume  represents  the  amount  of  0.  The  remainder  of  the  gas  present 
represents  N. 


Fig.  236.— Haywood's  Experiment. 


FiO.  237.-60863  collected 
over  mercury,  A  ball  of 
caustic  potash  absorb- 
ing the  CO2. 


There  are  other  methods  of  estimating  the  proportion  of  the  gases,  but  this 
simple  experiment  is  suflBcient  to  explain  the  general  principle  on  which  such 
estimations  are  made.  Of  course  there  are  corrections  for  temperature  and 
pressure,  and  other  precautions  which  require  to  be  taken,  but  we  do  not  enter 
into  these  here.     (See  Appendix.) 

A  simple  form  of  gas-pump  has  been  devised  by  L.  Hill  {Journ.  of  Fhys.,  xvii. 
P-  353)'  by  means  of  which  results  of  sufficient  accuracy  are  obtained  from  10 
cc.  of  blood. 

6.  Analysis  of  Expired  Air  by  Hempel's  Method.  ^ 

A  burette,  A  (fig.  238),  containing  100  cc,  and  graduated  into  tenths  ot 
a  cc,  is  used  to  measure  the  expired  air.  It  communicates  below  by  means 
of  an  india-rubber  tube  with  the  movable  tube  or  reservoir  for  water,  B. 
Above,  A  is  connected  to  an  absorption  pipette  bv  means  of  a  short  india- 
rubber  tube  of  1-2  mm.  diameter  with  thick  walls,  and  provided  with  a 
Mohr's  clip.  The  tube,  a.,  is  piacea  in  connection  successively  with  the 
pipettes,  px,  which  contain  a  solution  of  caustic  potash  to  absorb  the  CO2 
and  fig.  239,  which  contains  sticks  of  red  phosphorus  in  water  to  absorb  the  0. 

*  Methods  q/ Gas  Analysis,  by  W.  Hempel.     London,  1892. 


3H 


PRACTICAL  PHYSIOLOGY. 


[lxvi. 


Suppose  the  gas  to  be  collected  in  A  ;  measure  its  amount  when  B  is  so 
placed  that  the  level  of  the  acidulated  water  is  equal  in  both. 

Remove  the  Mohr's  clip  from  a,  raise  B,  and  force  all  the  air  into  p.  Then 
lower  B,  and  withdraw  unabsorbed  air  from  p.     Measure  the  volume  of  air. 

Connect  A  now  with  the  phosphorus  pipette  and  force  the  air  into  it  by 
again  raising  B.  Lower  B,  and  estimate  the  remaining  volume  of  air.  In 
each  case  the  difference  of  the  volume  of  air  corresponds  to  the  quantity  of 
gas  absorbed. 


.«5 
aP 


otash  Pipette  to  absorb  the  C02- 


Fid.  239.— Rpette  with  Phosphom* 
to  absorb  the  Oxygen. 


The  temperature,  of  A  can  be  kept  constant  by  placing  it  in  a  wide  tube 
through  which  water  is  kept  circulating  as  in  a  Liebig's  condenser. 

7.  Waller's  modification  of  Zuntz's  apparatus  is  very  convenient  (Waller's 
Human  Physiolony,  2nd  Ed.,  p.  I2)).  In  this  apparatus,  the  measuring  tube 
is  filled  by  means  of  a  bulb,  and  not  a  long  tube,  and  the  measuring  tube  has 
on  it  above  a  bulb  which  communicates  by  means  of  three  tubes  guarded  by 
simple  taps  ;  two  of  these — horizontal — go  to  the  two  absorption  (0  and  CO2) 
pipettes,  while  the  vertical  one  is  an  outlet  tube.  (The  apparatus  is  made  by 
Baird  k  Tatlock.) 


LXVII.]  LARYNGOSCOPE.  315 

LESSON  LXYIL 

LARYNGOSCOPE— VOWELS. 

1.  The  Laryngoscope  is  used  to  investigate  the  condition  of  the 
pharynx,  larynx,  and  trachea.  Various  forms  are  in  use,  but  they 
all  consist  of — (i)  One  or  more  small,  usually  circular,  plane  mirrors 
fixed  to  a  metallic  rod  at  an  angle  of  120° ;  the  metallic  rod  fits 
into  a  suitable  handle,  and  is  fixed  by  means  of  a  screw.  (2)  A 
large  concave  mirror  of  about  20  cm.  focus,  perforated  with  a  hole 
in  the  centre,  and  secured  to  the  operator's  forehead  by  means  of  a 
circular  band  passing  round  the  head.  The  mirror  itself  is  fixed 
in  a  ball-and-socket  joint,  so  that  it  can  be  moved  freely  in  every 
direction. 

A.  Practise  first  of  all  on  a  model  of  the  head  and  larynx 
provided  for  the  purpose. 

B.  On  a  Living  Person. — (a.)  Place  the  patient  upright  in  a 
chair.  A  good  source  of  artificial  light — e.(/.,  a  suitable  Argand 
lamp — is  placed  near  the  side  of  the  patient's  head,  a  little  above 
the  level  of  his  mouth.  The  incandescent  lamp  gives  a  brilliant, 
clear,  and  steady  light.  INIackenzie's  rack-movement  lamp  is  a  most 
convenient  form.  The  observer  seats  himself  opposite  and  close  to 
the  patient;  places  the  large  mirror  on  liis  forehead,  and  either 
looks  through  the  central  hole  in  it  with  one  eye,  or  raises  it  so 
that  he  can  just  see  under  its  lower  edge. 

(b.)  Seated  in  front  of  the  patient,  the  observer  directs  a  beam 
of  light  until  the  lips  of  the  patient  are  brightly  illuminated.  The 
patient  is  then  directed  to  incUne  his  head  slightly  backwards,  to 
open  his  mouth  wide,  and  protrude  his  tongue.  Place  a  clean 
handkerchief  over  the  tongue,  and  give  the  patient  the  hand- 
kerchief to  hold,  which  secures  that  the  tongue  is  kept  protruded 
and  well  forward.  Move  the  large  mirror  until  the  uvula  and 
back  of  the  throat  are  brightly  illuminated,  the  operator  moving 
his  head  slightly  to  and  from  the  patient  until  the  greatest 
brightness  is  obtained. 

(c.)  Take  the  small  laryngeal  mirror  in  the  right  hand,  and  warm 
it  gently  over  the  lamp  to  prevent  the  condensation  of  moisture  on 
its  surface.  Test  its  temperature  on  the  skin  of  the  cheek  or  the 
back  of  the  hand.  Holding  the  handle  of  the  mirror  as  one  does  a 
pen,  rapidly  carry  it  horizontally  backwards,  avoiding  contact  with 
any  structures  in  the  mouth,  until  its  back  rests  against  the  base  of 
the  uvula.     At  the  same  time,  direct  the  beam  of  light  upon  the 


3i6 


PRACTICAL  PHYSIOLOGY, 


[LXVII. 


laryngeal  mirror,  when  an  inverted  image  of   the  larynx  will  be 
seen  more  or  less  perfectly. 

(d.)  By  moving  the  laryngeal  mirror,  not,  however,  pressing  too 
much  on  the  uvula,  or  continuing  the  observation  for  too  long  a 
time,  one  may  explore  the  whole  of  the  larynx.  Perhaps  only  the 
posterior  part  of  the  dorsum  of  the  tongue  is  seen  at  hrst ;  if  so, 
slightly  depress  the  handle  of  the  mirror,  when  the  curved  fold  of 
the  shghtly  yellowish  epiglottis  and  its  cushion,  with  the  glosso- 
epiglottidean  foldSj  come  into  view.  In  the  middle  line  are  the 
tru£  vocal  cords,  which  are  pearly  white  and  shining,  and  best  seen 
when  a  high  note  is  uttered,  and  between  them  the  cliink  of  the 
glottis.  Above  these  are  the  false  vocal  cords,  which  are  red  or 
pink,  the  ary-epiglottidean  folds,  with  on  each  side  the  cartilages  oj 
Wrisherg  farthest  out,  the  cartilages  of  Santorini  internal  to  this, 
and  the  arytenoid  cartilages  near  the  middle  line  (figs,  240,  241). 


Flo.  94a— View  of  the  Larynx  daring  • 
Deep  Inspiration,  g.e.  Glosso-epi- 
plottidean  fold;  I.e.  Lip  and  cushion 
of  epiglottis;  a.e.  Ary- epiglottic 
fold;  C.W.,  r,.S.  Cartilages  of  "Wris- 
herg and  Santorini :  v.c.  Vocal  cord ; 
v.b.  Ventricular  band :  p.v.  Processus 
vocalis;  e.r.  Cricoid  cartilage;  i. 
Rings  of  trachea. 


Flo.  «4T.— LaTynx  during  Vocalisation. 
f.i.  Fossa  innominata ;  h.f.  Hyoid 
fossa;  com.  Arytenoid  commissure. 


(e.)  Make  the  patient  sing  a  deep  or  high  note,  or  inspire  feebly 
or  deeply,  and  observe  the  change  in  the  shape  of  the  glottis.  On 
uttering  a  deep  note,  the  rings  of  the  trachea  may  be  seen.  N.B. — 
Remember  that  what  is  seen  by  the  observer  in  the  laryngeal 
mirror  on  his  right  or  left  corresponds  to  the  patient's  left  and 
right.  The  lower  part  of  the  mirror  gives  an  image  of  the  more 
posterior  structures,  while  the  anterior  structures  are  reflected  in  its 
upper  part. 

2.  Auto-Laryngoscopy, — The  student  should  learn  to  use  the  laryngoscope 
on  himself.  The  student  sits  in  a  chair,  fixes  the  large  reflecting  mirror  in  & 
suitable  holder  about  eighteen  inches  in  front  of,  and  on  a  level  with  his 
mouth.  Behind  and  to  one  side  of  this  an  ordinary  plane  mirror  is  placed 
vertically.     On  one  side  of  his  head  he  places  the  source  of  hght.     The  light 


lxvil] 


LARYNGOSCOPE. 


317 


is  reflected  on  to  the  uvula  by  the  reflecting  mirror,  and,  on  introducing  the 
small  laryngeal  mirror,  by  a  little  adjustment  one  sees  the  image  of  the 
larynx  in  the  plane  mirror.  Or  one  may  use  in  a  similar  way  the  apparatus 
of  Foulis.  In  Dr  George  Johnson's  method,  the  ordinary  reflector  is  strapped 
on  to  the  forehead,  and  the  observer  i)laces  himself  in  front  of  a  toilet  mirror. 
In  a  line  with  and  slightly  behind  the  mirror,  and  on  one  side  of  the  observer 


Fig.  242.— Konig's  Manometric  Flame  Apparatus. 

place  a  lamp.  By  means  of  the  reflector,  the  image  of  the  fauces  seen  in  the 
mirror  is  illuminated.  Introduce  the  laryngeal  mirror,  when  the  image  of  the 
larynx  is  seen  in  the  toilet  mirror. 

3.  Analysis  of  Vowel  Sounds. 

Use  Konig's  ap])aratus,  as  shown  in  fig.  242.  Connect  the  tube  of  the 
capsule  with  the  gas  supply,  light  the  gas-jet,  and  sing  the  vowels  A, 
E,  I,  0,  U  in  front  of  the  0])en  trumpet-shaped  tube  shown  in  the  figure. 
With  the  other  hand  rotate  the  mirror  (M),  and  observe^  the  serrated  reflec- 
tion of  the  flame  in  the  mirror,  noticing  how  the  image  in  the  mirror  varies 
with  each  vowel  sounded. 


3l8  PRACTICAL  PHySIOLOGT.  [LXVIIL 


PHYSIOLOGY  OF  THE  CENTRAL  NERVOUS 
SYSTEM. 


LESSON  LXYIIL 


REFLEX  ACTION— ACTION  OF  POISONS- 
KNEE-JERK. 

1.  Reflex  Action. — Destroy  the  brain  of  a  frog  down  as  far  aa 

the  medulla  oblongata,  which  should  be  done  without  loss  of  blood. 
Place  under  a  bell-jar  a  normal  frog  for  comparison.  Immediately 
the  frog  is  pithed,  on  pmching  one  of  its  toes,  very  probably  the 
leg  will  not  be  drawn  up.  After  half  an  hour  or  more  (by  this 
time  it  has  recovered  from  the  shock  of  the  operation),  observe — 

(a.)  Its  attitude :  the  head  of  the  pithed  frog  lies  on  the  plate 
on  which  it  is  placed,  while  in  the  intact  frog  the  head  is  erect, 
the  body  and  head  forming  an  acute  angle  with  the  surface  on 
which  the  frog  rests. 

(h.)  Its  eyes  are  closed,  while  those  of  the  intact  frog  are  open. 
The  fore-limbs  are  either  .flexed  and  drawn  under  the  chest,  or 
spread  out,  so  that  the  body  is  no  longer  supported  on  the  nearly 
vertical  fore-limbs,  as  in  the  intact  frog,  but  lies  flat  upon  the 
surface  of  support.     The  legs  are  pulled  up  towards  the  body. 

(c.)  The  absence  of  respiratory  movements  in  the  nostrils  and 
throat.  It  makes  no  spontaneous  movements,  if  left  entirely  to 
itself. 

(d.)  Turn  it  on  its  back  :  it  lies  in  any  position  it  is  placed.  Do 
this  witli  a  normal  frog ;  the  latter  regains  its  equilibrium  at  once. 
Extend  one  of  the  legs ;  it  will  be  drawn  up  again  towards  the 
body.  Pinch  the  flank  with  a  pair  of  forceps  ;  the  leg  of  the  same 
side  is  rapidly  extended,  then  drawn  up  towards  the  spot  stimulated. 
Pinch  sharply  the  skin  round  the  anus  with  forceps.  Immediately 
both  legs  are  pushed  out  and  pulled  up  towards  the  body,  as  if  to 
dislodge  the  ofi'ending  body. 

2.  Bend  a  long  (6  cm.)  straight  pin  into  the  form  of  a  hook, 
and  push  it  through  the  tips  of  both  jaws,  and  by  means  of  the 
hook  hang  up  the  frog  vertically  on  a  suitable  support.     At  first 


LXVIII.]  REFLEX  ACTION,  ETC.  3 19 

the  legs  may  make  a  few  movements,  but  they  soon  cease  to  do 
so,  and  hang  motionless. 

(a.)  Pinch  the  tip  of  any  toe  of  the  right  leg ;  the  right  leg  is 
drawn  up.  If  a  toe  of  the  left  leg  be  pinched,  the  left  leg  is  drawn 
up.     These  are  unilateral  reflex  movements. 

(b.)  Mechanical  Stimuli. — Pinch  the  tip  of  one  toe  very  feeoiy, 
perhaps  only  the  foot  will  be  flexed  at  the  ankle-joint.  Pinch 
more  strongly,  and  a  greater  reflex  movement  will  be  obtained. 
It  is  evident,  therefore,  that  the  reflex  movement  varies  not  only 
with  the  part  of  the  skin  stimulated  (1,  d.),  but  also  with  the 
intensity  of  the  stimulus.  Very  violent  stimulation  may  cause 
reflex  movements  in  all  the  other  limbs.  This  is  due  to  irradiation 
of  the  reflex  movement  in  the  cord. 


3.  The  Latent  Period  (Tiirck's  Method).  Summation  of 
Stimuli. 

(a.)  Prepare  and  label  dilutions  of  sulphuric  acid  containing 
I,  2,  3,  and  4  cc.  per  Utre — i.e.,  o.i,  0.2,  0.3,  and  0.4  per  cent 
of  sulphuric  acid  (by  volume) — and  place  some  of  each  in  lour 
shallow  glasses.  Arrange  also  a  large  beaker  of  water  to  wash  the 
frog.  Adjust  a  metronome  to  beat  one  hundred  times  per 
minute.     Cause  it  to  beat. 

(h.)  Hold  the  frog  in  the  left  hand  by  means  of  the  hook,  and 
in  the  right  take  a  glass  rod  to  hold  one  leg  aside.  Dip  the  other 
leg  up  to  the  ankle  into  the  o.  i  per  cent,  acid,  and  on  doing  so 
count  the  number  of  beats  before  it  is  withdrawn  from  the  acid. 
After  the  leg  is  withdrawn,  wash  the  leg  in  water  to  remove  the 
9,cid.  Note  the  time  in  hundredths  of  a  minute,  i.e.,  the  latent 
period.  Allow  the  frog  to  rest  at  least  five  minutes,  and  repeat 
the  experiment.  Take  the  mean  of  the  two  observations  —or,  if 
you  prefer  it,  of  three  or  more  observations — and  this  will  give  the 
"  latent  period." 

(r.)  Repeat  with  suitable  intervals  of  repose  the  same  experi 
ment  with  acid  of  0.2,  0.3,  and  0.4  per  cent.,  noting  that,  as  thv 
strength  of  the  acid  increases,  the  latent  period  becomes  shorter, 
but  not  in  the  ratio  in  which  the  acid  is  stronger. 

(d.)  If  only  the  longest  toe  is  dipped  into  the  acid,  then  the 
summation  of  stimuli  takes  place  more  slowly. 

4.  Chemical  Stimulation.     (Purposive  Characters  of  Reflex.) 
(a.)  In  a  small  glass  place  some  strong  acetic  acid  and  a  few 

pieces  of  filter-paper  3  mm.  square.  Either  when  the  frog  is 
lying  on  its  back  or  while  it  is  suspended,  apply  with  a  pair  of 
forceps  one  of  the  pieces  of  paper  moistened  with  acid — the  surplus 


320  PRACTICAL   PHYSIOLOGY.  [lXVIII. 

removed — to  the  skin  on  the  inner  side  of  the  thigh.  At  once 
the  leg  on  that  side  is  violently  drawn  up,  perhaps  both  legs  are 
drawn  up,  and  the  foot  of  the  leg  first  drawn  up  is  swept  over  the 
spot  stimulated,  as  if  to  remove  the  piece  of  paper,  i.e.,  purposive, 
co-ordinated  movements  are  executed.  At  once  dip  the  frog  in 
water  to  remove  the  acid ;  allow  it  to  rest  for  some  time.  It  is 
much  easier  to  obtain  irradiation  of  the  reflex  movements  by 
chemical  than  by  mechanical  stimuli. 

(6.)  After  five  minutes  repeat  the  experiment,  but  hold  the  leg 
to  which  the  acid  is  applied.  Probably  the  other  leg  will  move, 
and  the  opposite  foot  will  remove  the  irritating  acid  paper.  Wash 
the  frog  and  allow  it  to  rest. 

(c.)  Test  further,  by  applying  papers  to  the  flank,  the  skin  over 
the  gastrocnemius,  Sac,  and  in  all  cases  characteristic  but  diflTerent 
reflex  movements  will  be  elicited, if  sufficient  interval  for  recovery 
(five  minutes  at  least)  be  allowed  between  the  successive  experi- 
ments. 

(c?.)  Destroy  the  spinal  cord,  all  reflex  action  is  abolished.  The 
nerves  and  rausclesretaintheirexcitabilityand  the  heart  continues 
to  beat.  Expose  the  heart :  it  beats.  Muscle  and  nerve  respond 
to  electrical  and  other  stimuli. 

5.  Action  of  Strycliniiie. 

(a.)  Using  a  frog  with  its  brain  destroyed,  inject  with  a  fine  glass 
pipette  or  a  hypodermic  syringe  into  the  dorsal  lymph  sac  a  drop 
of  dilute  solution  of  acetate  of  strychnine  (0.5  per  cent.). 

(6.)  Observe  that  as  soon  as  the  poison  is  absorbed — i.e.,  within 
a  few  minutes — cutaneous  stimulation  of  any  part  of  the  body, 
even  tapping  the  table,  excites  general  violent  tetanic  spasms,  and 
not  co-ordinated  muscular  responses,  of  the  whole  body.  During 
the  convulsive  paroxysm  the  limbs  are  extended,  hard,  and  rigid, 
while  the  trunk  is  similarly  affected.  The  extensor  muscles  are 
more  affected  than  the  flexors.  The  tetanic  paroxysm  passes  off, 
to  be  soon  followed  by  another  on  the  slightest  stimulation. 
The  excitability  has  been  so  greatly  increased  that  even  the 
slightest  stimulus  applied  to  the  skin  discharges  a  reflex  spasm, 
i.e.,  provokes  muscular  responses  which  are  maximal,  so  that  a 
minimal  stimulus  produces  a  maximal  response. 

(c.)  Destroy  the  spinal  cord  with  a  seeker  or  long  pin.  At 
once  the  spasms  cease.  Strychnia,  therefore,  acts  on  the  cord 
directly,  and  not  on  the  muscles  and  nerves. 

{(l.)  In  another  frog,  divide  the  cord  below  the  bulb,  the  brain 
in  front  being  destroyed,  but  the  cord  intact.  Apply  a  crystal 
of  sulphate  of  strychnia  to  the  cord.  It  soon  causes  tetanic 
spasms,  thus  showing  that  strychnine  affects  the  cord. 


LXVIIT.]  REFLEX   ACTION,   ETC.  321 

6.  Action  of  Potassium  Chloride  or  Bromide  or  Chloral. 

Prepare  a  reflex  frog  as  in  Lesson  LXVIII.  1.  Test  the  latent  period 
with  dilute  sulphuric  acid,  0,2  i)er  cent.,  until  constant  results  are  obtained. 
Inject  2  minims  of  a  i  per  cent,  solution  of  KCl  or  KBr  or  C2HCI3O,  and 
after  ten  minutes  time  again  test  the  latent  ])eriod.  Within  a  short  time  the 
latent  period  will  be  greatly  prolonged.  Plot  a  curve  of  the  results,  the 
abscissa  to  mark  time  and  the  ordinates  the  length  of  the  latent  period. 

7.  Electrical  Stimulation. 
(A.)  Single  Induction  Shocks. 

(a.)  From  the  secondary  coil  (key  interposed)  apply  two  fine 
wire  metallic  electrodes,  in  the  form  of  two  loops,  to  the  skin  of  the 
leg,  the  electrodes  being  about  .5-1  cm.  apart. 

{h.)  Stimulate  with  different  strengths  of  current.  No  reflex 
response.  A  single  induction  shock  does  not  discharge  a  reflex 
movement. 

(B.)  Repeated  Shocks. 

(a.)  Leave  the  electrodes  in  situ,  but  adjust  the  coil  for  repeated 
shocks.  On  applying  a  succession  of  even  feeble  shocks,  a  reflex 
response  is  readily  obtained.     Make  a  table  of  the  results  obtained. 

{/>.)  Expose  the  sciatic  nerve  without  injuring  the  adjacent  parts ; 
on  stimulating  the  skin  of  the  foot  or  leg  as  before,  a  reflex  response 
is  readily  obtained,  but  on  stimulating  the  sciatic  nerve  directly 
under  the  same  conditions,  there  may  be  no  response  until  the 
current  is  made  distinctly  stronger.  This  result  is  explained  (?)  by 
stating  that  the  peripheral  terminals  are  more  excitable  than  the 
nerve  trunk,  while  others  assume  that  in  the  sciatic  nerve,  besidas 
excito-motor  (reflex)  fibres,  there  are  nerve-fibres  which  inhibit  the 
action  of  such  fibres.  It  is  said  that  very  strong  stimulation  of 
cutaneous  nerves  also  excites  the  reflex-inhibitory  lilires. 

(''.)  Isolate  any  one  of  the  nerves  traversing  the  dorsal  lymph- 
sac  of  a  frog,  but  leave  a  small  square  of  skin  attached  corresponding 
to  the  terminals  of  the  nerve.  Apply  repeated  shocks  directly  to 
the  nerve,  in  all  prolmbility  there  will  be  no  reflex  response,  but  if 
the  skin  be  touched  with  dilute  acetic  acid,  response  will  probably 
take  place.  If,  however,  strong  sulphuric  acid  be  applied  to  the 
skin,  there  will  be  no  response. 

8.  Knee-Jerk. 

(^/.)  Sit  on  a  chair  and  cross  the  right  leg  over  the  left  one. 
With  the  tips  of  the  fingers  or  a  percussion-hammer  strike  the 
right  ligamentum  patellae.  The  riglit  leg  will  be  raised  and  thrown 
forward  with  a  jerk,  owing  to  the  contraction  of  the  quadriceps 
muscle.  An  appreciable  time  elapses  between  the  striking  of  the 
tendon  and  the  jerk.  The  knee-jerk  is  almost  invariably  absent  in 
cases  of  locomotor  ataxia,  while  it  is  greatly  exaggerated  in  some 

X 


322  PRACTICAL  PHYSIOLOGY.  [LXIX. 

other  nervous  afFections ;  so  that  its  presence  or  absence  is  a  most 
important  clinical  symptom. 

(b.)  The  knee-jerk  is  readily  obtained  in  a  rabbit. 

9.  By  means  of  the  hand  compress  the  abdominal  aorta  of  a  rabbit  for  a  fe^ 
minutes.  There  results  temporary  paralysis  of  both  hind-legs  or  paraplegia. 
Soon  after  the  circulation  is  restored  in  the  cord  and  lower  limbs,  the  para- 
plegia disappears. 


LESSON  LXIX. 
SPINAL  NERVB-ROOTS. 


1.  Functions  of  the  Roots  of  the  Spinal  Nerves. — To  expose  the  roots, 
destroy  the  brain  of  a  frog,  lay  it  on  its  belly,  and  make  a  median  incision  in 
the  skin  of  the  back,  from  the  neck  to  the  upper  end  of  the  urostyle.  Turn 
back  the  flaps  of  skin,  and  carry  the  incision  down  to  the  spines  of  the 
vertebrae.  With  a  scraper  or  blunt  knife  remove  the  muscles  along  each  side 
of  the  vertebral  column,  so  as  to  lay  bare  the  arches  of  the  vertebra?.  With 
a  blunt-pointed  pair  of  scissors,  or  two  saw-blades  parallel  to  each  other  and 
fitted  at  a  suitable  distance  into  a  handle,  as  devised  by  Ludwig,  cut  through 
the  arches  of  the  eighth  or  last  vertebra,  taking  care  not  to  injure  the  nerves 
within  the  spinal  canal.  Remove  successively  from  below  upwards  the  seventh, 
sixth,  and  fifth  vertebral  arches,  when  the  tenth,  ninth,  and  eighth  spinal 
nerve-roots  will  come  into  view.  The  posterior  roots  are  larger,  come  first 
into  view,  and  cover  the  anterior.  The  roots  may  be  separated  by  a  seeker. 
Select  the  largest  posterior  root— the  ninth — and  with  an  aneurism  needle 
carefully  place  a  fine  silk  thread  (say  a  red  one)  under  it. 

{a. )  tighten  the  ligature  near  the  cord,  and  observe  movement  in  some  part 
of  the  body.  Divide  the  nerve  between  the  cord  and  the  ligature,  and  observe 
further  movements  on  division. 

{b. )  With  the  thread  gently  lift  up  the  peripheral  or  distal  end  of  the  nerve- 
root,  place  it  on  well-protected  electrodes,  and  stimulate  it  with  an  inter- 
rupted current.     No  movement  is  observed  in  the  muscles  of  the  limb. 

(c.)  Select  the  posterior  root  of  the  eighth  nerve,  ligature  it  at  some  distance 
from  the  cord,  and  divide  it  on  the  "distal  side  of  the  ligature.  There  is 
neither  contraction  of  the  muscles  of  the  leg  nor  movement  of  the  body. 
Place  the  central  stump,  i.e.,  the  part  still  connected  with  the  cord,  on  the 
electrodes,  and  stimulate  it,  when  movements  \sdll  take  place  in  several  parts 
of  the  body, 

{d. )  Divide  the  posterior  roots  from  the  seventh  to  the  tenth  nerves,  deserve 
that  the  leg  on  that  side  has  become  insensible.  Turn  aside  the  roots  of 
the  divided  nerves,  and  expose  the  anterior  roots,  which  are  very  thin  and 
slender.  Repeat  the  preceding  experiments  on  the  anterior  root  of  the  ninth 
nerve,  i.e.,  place  a  ligature  round  it,  tighten  the  ligature,  and  divide  the 
nerve  between  the  cord  and  the  ligature.  Stimulate  the  distal  end  with  an 
interrupted  current ;  this  causes  contraction  of  the  muscles  supplied  by  this 
root. 

From  the  effects  of  section  and  stimulation  of  the  nerve-roots,  one  concludes 
that  the  anterior  are  motor,  and  the  posterior  are  sensory.  (E.  Steinach, 
"  Motorische  Functionen  hint.  Spinal nervenwurzeln,"  Pfliiger's  Arch.,  Bd.  66, 
p.  593-) 


LXX.]  BEACTION-TIMK.  323 

LESSON  LXX. 

RBAOTION-TIMB— CEREBRAL  HEMISPHERES. 

Reaction-Time  is  the  interval  that  elapses  between  the  applica- 
tion of  a  stimulus  to  a  sense-organ  and  the  moment  the  stimulus 
is  responded  to  by  the  individual.  For  simple  reaction-time,  or 
sensori-motor  reaction-time,  all  discrimination  and  choice  are  elimi- 
nated by  repeating  the  same  sensation  and  using  the  same  response. 
Rutherford's  results  {Proc.  Roy.  Sor.  Edin.,  July  10,  1894)  give 
rather  longer  periods  than  some  German  observers.  He  finds  the 
pendulum-myograph  very  advantageous  in  experiments  on  hearing 
and  touch,  as  successive  curves  can  be  superimposed.  The  mean 
reaction-time  he  found  to  be,  for  sight,  o.2o"-o.2  2";  hearing, 
0.1 5' -0.1 6";  touch,  o.i4"-o.i5"  ^cheek),  o.i^"-o.i8"  (skin  of 
finger). 

Reaction-Time  for  Touch  in  Man. 

1.  Pendulum-Myograph  Method  {Rutherford). 

Two  persons  are  required,  and  the  observed  person  should  not 
see  what  the  observer  is  doing. 

(a.)  Arrange  the  apparatus  as  in  fig.  243.  The  stimulation  is 
done  always  at  the  same  moment  when  the  pendulum  in  its  swing 
breaks  the  primary  circuit.  It  is  convenient,  as  shown  in  the 
figure,  to  use  an  electro-magnet  for  releasing  the  pendulum. 

{h.)  The  electrodes  from  the  secondary  coil  are  applied  to  any 
part  of  the  skin,  and  the  observer,  when  he  feels  the  shock,  closes 
the  "  response  key,"  whereby  a  mark  is  made  on  the  gla«s  plate. 
Time  should  be  recorded  on  the  plate  beforehand  (60  or  100  D.Y. 
per  second). 

(c.)  If  it  is  desired  for  sound,  a  telephone  is  placed  in  the 
secondary  circuit  and  the  observed  person  responds  when  he  hears 
the  click  at  the  moment  of  breaking  the  primary  circuit. 

Fig.  244  shows  the  result  obtained  for  the  reaction-times  for 
touch  by  the  pendulum-myograph  method  (fig.  243),  chronograph  60 
D.V.  per  second.  The  vertical  line  indicates  the  moment  at  which 
an  induction  shock  was  given  to  (i)  skin  of  left  cheek ;  (2) 
left  side  of  neck ;  (3)  left  upper  arm  at  insertion  of  deltoid ;  (4) 
left  little  finger ;  (5)  dorsum  of  left  foot  at  root  of  toes.  Response 
signal  was  always  given  by  right  forefinger.  The  vibrations 
following  each  signal  of  response  result  from  the  momentum  of  the 
lever  {Rutherford), 


324 


PRACTICAL  PHYSIOLOGY. 


[LXX. 


2.  Recording  on  Dmm  (also  for  sight  and  hearing). 

(a.)  Another  method  is  to  cause  two  electro-magnets  with  writing- 
styles  to  record  on  a  rapidly  moving  drum  arranged  as  in  fig.  245. 
One  signal  is  interposed  in  the  primary  circuit  of  an  induction  coil, 
with  a  contact-key  also  in  the  circuit.  This  is  the  "stimulating 
key." 

(h.)  The  other  electro-magnet  is  in  connection  with  a  battery, 
a  contact-key  being  in  the  circuit — the  "response  key."     If  tlua 


Fig.   243— Rutherford's  Scheme  of  using       FlO.  244.— Result  obtained  for  Simple  Re- 
Penduliim-Myo^iraph    for    Estimating  action-Time  with  Pendulum-Myograph 

Simple  Reaction-Time.  (Rutherford).    Shock  applied  in  (i)  To 

skin  of  left  cheek ;  (2)  Left  side  ot 
neck ;  (3)  Left  upper  arm  near  deltoid  ; 
(4)  Left  little  finger ;  (5)  Dorsum  of  left 
foot. 

method  be  used  for  touch,  the  electrodes  from  the  secondary  coil 
are  applied  to  some  part  of  the  skin,  and  the  person  marks  response 
with  the  response  ke3\ 

(c.)  If  for  sight,  a  white  piece  of  paper  (Rutherford)  is  placed  on 
the  electro-magnet  style  in  the  primary  circuit,  and  the  person 
responds  when  he  sees  this  move,  which  it  does  when  the  primary 
circuit  is  made. 

{d.)  If  for  hearing,  then  a  telephone  is  introduced  into  the 
etimuiating  circuit.     The  observer  puts  the  telephone  to  his  ear, 


LXX.] 


REACTION-TIME. 


325 


and  responds  when  he  hears  in  the  telephone  the  click  of  the 
induction  shock  due  to  closure  of  the  primary  circuit.  Of  course,  a 
chronograph  records  time. 

3.  Reaction-Time  for  Touch  in  Man. — Two  persons  and  the 
following  apparatus  are  required  :  coil,  batteries,  wires,  two  Du 
Bois  keys,  two  electro-magnets  to  record,  and  tuning-fork  vibrating 
100  D.Y.  per  second. 

(a.)  Arrange  the  experiment  as  in  fig.  246,  i.e..,  in  the  primary 
circuit  (single  shocks),  two  keys  arranged  in  the  course  of  one 
wire,  and  a  recording  electro- 
magnet. Under  the  latter  is 
placed  a  chronograph  recording 
j-^",  the  point  of  the  one 
exactly  under  the  other,  the 
cylinder  moving  at  a  rapid 
rate. 

{h.)  Of  the  two  persons,  A 
and  B,  suppose  B  to  be  experi- 
mented on.  The  electrodes 
are  placed  say  on  the  back  of 
the  hand  or  cheek  of  B,  and 
he  has  control  of  key  marked 
P,  while  A  controls  0.  Begin 
with  0  open,  and  P  closed. 
The  observer  closes  0,  this 
completes  the  primary  circuit, 
the  style  of  the  chronograph  is 
attracted,  descends  and  makes 
a  slightly  obUque  mark  on  the 
paper,  which  indicates  the 
moment   of   stimulation.      As 

soon  as  B  feels  this  he  opens  key  P,  the  primary  current  is  broken 
and  the  recording  lever  rises. 

((.'.)  Measure  the  time  value  between  the  down  and  up  movements 
of  the  recording  lever.  In  this  case  the  individual  operated  on 
knows  the  spot  to  be  stimulated,  but  even  with  all  his  attention 
the  results  may  not  be  constant.  The  time  varies  with  the 
individual,  his  state  of  attention,  fatigue,  part  stimulated,  and  many 
other  factors. 

4.  The  Dilemma. — When  the  individual  has  to  make  a  deliberate 
choice  between  what  parts  of  the  body  are  stimulated,  then  the 
reaction-time  is  considerably  longer. 

The  experiment  is  arranged  as  in  fig.  246,  save  that  the  wires 


FlO.  245.— Arrangement  for  Simple  Reaction- 
Time  {Rutherford). 


326 


PRACTICAL  PHYSIOLOGY. 


[LXX. 


from  the  secondary  coil  pass  to  a  Pohl's  commutator  without  cross- 
bars, and  provided  with  two  pairs  of  electrodes.  Thus  at  will  the 
observer  can  pass  the  induced  shock  either  through  the  one  pair  or 
the  other,  the  individual  experimented  on  not  knowing  when  the 
reverse!  is  changed. 


e^Hr"^ 


^r" 


Fig.  246.— Eeactlon-Tlme  for  Touch  in  Man.    T.  Time  signal  in  cireoit  with  a  tuning-fork, 
vibrating  loo  D.V.  per  second. 

5.  The  Nenramoebimeter  {Exner),  or  Psychodometer  {Oberstein),  consists 
of  two  uprights  (S),  with  a  horizontal  axis  carrying  a  spring  (F)— which 
vibrates  100  D.V.  per  second — with  a  writing-style  at  its  free  end  (fig.  247). 
A  brass  plate  (B — b)  moves  in  a  slot,  and  carries  a  smoked  glass  plate  (T),  a 
catch  (DG),  and  a  handle  (H).     The  handle  (H)  pushes  up  the  glass  plate  and 


Fia.  S47.— The  Nenramoeblmeter. 

catch  (G)  until  the  latter  meets  the  spring  (F),  and  puts  (F)  on  the  stretch. 
When  the  catch  (G)  is  withdrawn,  (F)  vibrates,  and  if  the  style  be  arranged 
to  touch  the  glass,  a  curve  is  obtained  on  the  latter. 

(n.)  It  requires  two  persons.  The  observed  person  places  a  finger  on  the 
knob  (K\  while  the  catch  (G)  and  glass  plate  are  pushed  up,  the  former  to 
catch  on  (F),  and  the  style  is  arranged  to  write  on  the  glass.  The  observed 
person  must  not  look,  bat  close  his  eyes  and  listen. 


LXX.]  REACTION-TIME.  327 

(b.)  The  observer  suddenly  pulls  on  (H),  thus  dischargiHg  the  spring  (P), 
which  vibrates  and  produces  a  note.  The  moment  the  observed  person  hears 
the  sound,  he  presses  the  knob  (K)  and  raises  the  writing-st3'le.  Of  course, 
a  curve  is  recorded,  and  it  is  easy  to  calculate  the  time  which  has  elapsed 
uetween  the  emission  of  the  sound  and  the  reaction  by  the  observed  person. 
Numerous  observations  must  be  made,  and  the  mean  taken. 

(c.)  The  instrument  may  also  be  used  for  vision,  i.e.,  when  the  slide  (B — b) 
on  being  moved  uncovers  a  painted  disc. 

{d.)  In  the  more  complete  form  of  the  apparatus,  a  key  is  fixed  on  one  side 
of  the  apparatus,  so  that  an  electrical  current  is  made  or  broken  at  the 
moment  the  spring  begins  to  vibrate.  The  key  is  placed  in  the  primary 
circuit  of  the  induction-machine,  and  the  electrodes  of  the  secondary  battery 
are  applied  to  any  part  of  the  skin,  the  observed  person  depressing  the  knob 
(K)  when  he  feels  the  stimulus.  One  can  thus  make  numerous  experiments 
on  the  "  Reaction-Time  "  from  diflferent  parts  of  the  body, 

W.  G.  Smith  has  devised  another  simple  method  (see  Journal  of  Physiology f 
xvii. ;  Proceedings  0/  Physiological  Society,  Nov.  1894). 

6.  Inhibition  of  Equilibration  Movements. 

Tak«  an  uninjured  frog,  place  it  on  its  back,  aad  observe  that  it  will  not 
lie  in  this  position,  but  immediately  rights  itself.  Tie  pretty  firmly  a  thick 
string  round  each  upper  arm.  This  in  no  way  interferes  with  the  movements 
of  the  frog  ;  but  on  placing  the  animal  on  its  back,  it  no  longer  rights  itself, 
but  continues  to  lie  in  this  position  for  a  long  time.  It  may  be  moved  or 
pulled  by  the  legs,  yet  it  does  not  regain  its  normal  attitude.  Notice  the 
modification  of  the  respiratory  movements. 

7.  Kircher's  Experimentum  Mirabile. 

(a.)  Take  a  hen  and  gently  restrain  its  movements.     Bring  its  bill  in  con- 
tact with  a  table.     "With  a  piece  of  white  chalk  draw  a  line  directly  outwards 
from  its  bill.     Hold  the  animal  steadily  for  a  few  seconds,  and  on  removing 
the  hands  gently,    it  will   be  found    that    the   hen  lies 
quiescent  and  does  not  move  for  a  considerable  time.     It  j\J/ 

may  be  rolled    to  one    side    or    the    other,   yet    it    lies  L  v) 

quiescent.  /i\ 

(6.)  Take  a  hen,  gently  restrain  its  movements,  then  lay  /    I  -V- — ^ 

a  straw  or  white  thread  over  the  base  of  its  bill.     In  a  short  >-A>< 

time  the  animal  becomes  quiescent.     Note  the  alteration  of         CX_l) ^ 

the  heart-beat  and  the  depth  and  number  of  tbe  respira-  Cf^fj ' 

tions.  *■-— \^r  / 

8.  Reactions  of  Frog  without  Cerebral  Hemispheres.  IJj     V 
In  the  frog,  as  shown  in  fig.  248,  the  parts  of  the  brain 

are  arranged  one  behind  the  other.  The  guide  on  the  ^ Fro^^?r^fabove^ 
surface  of  the  skull  to  the  posterior  end  of  the  cerebral  ^  Olfactory  bulb- 
hemispheres  is  a  line  connecting  the  front  margins  of  the  i.  Cerebral  hemi- 
two  exposed  tympanic  membranes.  The  brain  may  be  spheres ;  2.  Optic 
exposed  in  a  narcotised  frog  either  bv  means  of  a  small  beifum;^!  il^ed- 
trocar  or  by  severing  the  parts  with  a  knife.  After  removal  uUa  oblongata. 
of  the  cerebral  hemispheres,  place  a  little  cotton  wool  in 
the  wound  to  prevent  bleeding.  The  student  is  not  permitted  to  do  this 
operation. 

(a.)  Immediately  after  the  operation  the  frog  lies  flat  on  any  surface  with  its 
legs  extended,  but  after  the  shock  of  the  operation,  i.e. ,  in  about  an  hour,  it  draws 
up  its  legs  and  assumes  the  attitude  and  appearance  of  an  intact  frog,  but  it 


328  PRACTICAL  PHYSIOLOGY.  [LXX 

makes  no  spontaneous  movements,  although  it  responds  readily  to  external 
stimulation. 

{b. )  Its  eyes  are  open  and  its  respiratory  movements  continue  (p.  311 ). 

(c. )  If  placed  on  its  back,  it  immediately  rights  itself.  If  placed  on  the 
palm  of  the  hand,  or  on  a  rough  board  held  horizontally,  it  sits  immovable, 
but  if  the  board  be  tilted,  or  the  hand  rotated,  then,  when  a  certain  angle  is 
reached,  its  equilibrium  is  disturbed,  and  it  begins  to  crawl  up,  until  it  comes 
to  the  tx)p,  where  its  equilibrium  is  restored,  and  there  it  sits  motionless. 

(d.)  If  placed  in  water  it  makes  continuous  swimming  movements. 

{e.)  It  will  avoid  an  opaque  object  placed  in  front  of  it,  when  one  causes  it 
to  jump  by  pinching  its  hind-legs. 

(f. )  If  held  up  between  the  thumb  and  forefinger  of  the  right  hand  behind  the 
forearm,  and  if  it  be  pinched,  then  it  responds  to  every  pressure  by  a  "  croak." 
This  is  due  to  reflex  excitation  of  the  croaking  centre.  It  also  croaks  on 
stroking  the  skin  of  the  back  or  flanks, 

{g. )  It  does  not  feed  itselfl 

9.  Optic  Lobes  (Inhibition). 

(a.)  Expose  the  optic  lobes  in  a  frog,  after  removing  the  cerebral  hemi- 
Bpheres.  After  recovery,  determine  the  latent  })eriod  of  a  reflex  mechanical 
response  of  the  legs  by  Tlirck's  method  (Lesson  LXVIIL). 

{b. )  Apply  a  crystal  of  common  salt  to  the  optic  lobes,  and  then  determine 
the  latent  period.  It  is  greatly  increased,  or  the  reflex  may  be  suppressed 
altogether. 


LXXl.]  FORMATION  OF   IMAGE.  329 


PHYSIOLOGY  OF  THE  SENSE  ORGANS. 


LESSON  LXXI. 


FORMATION  OF  IMAGE  —  DIFFUSION  —  ABER- 
RATION —  ACCOMMODATION  —  SCHEINER'S 
EXPERIMENT  —  NEAR  AND  FAR  POINTS— 
PURKINJE'S  IMAGES— PHAKOSCOPE— ASTIG- 
MATISM—PUPIL. 

1.  Formation  of  an  Inverted  Image  on  the  Retina. 

(a.)  From  the  fresh  excised  ox-eye  remove  the  sclerotic  from 
that  part  of  its  posterior  segment  near  the  optic  nerve.  Roll  up  a 
piece  of  blackened  paper  in  the  form  of  a  tube,  black  surface  inner- 
most, and  place  the  eye  in  it  with  the  cornea  directed  forwards. 
Look  at  an  object — e.n.^  a  candle-flame — and  observe  the  inverted 
image  of  the  flame  shining  through  the  retina  and  choroid,  and 
notice  how  the  image  moves  when  the  candle  is  moved. 

[h.)  Focus  a  candle-flame  or  other  object  on  the  ground-glass  plate  of  an 
ordinary  camera  for  photographic  purposes,  and  observe  the  small  inverted 
image. 

{c.)  Fix  the  fresh  excised  eye  of  an  albino  rabbit  in  Du  Bois-Reymond's 
a])paratus  provided  for  you,  and  observe  the  same  phenomenon.  The  eye  is 
fixed  with  moist  modeller's  clay.  Observe  the  effect  on  the  retinal  image 
when  a  convex  or  concave  lens  is  placed  in  front  of  the  cornea.  These  lenses 
rotate  in  front  of  the  cornea,  and  are  attached  to  the  instrument. 

2.  Diffusion. 

{a.)  Fix  a  long  needle  in  a  piece  of  wood,  or  use  a  pencil  or 
penholder,  close  one  eye,  and  bring  the  needle  or  pencil  gradually 
nearer  to  the  other  eye.  After  a  time,  when  the  needle  is  five  to 
six  inches  distant,  it  will  no  longer  be  distinct,  but  blurred,  dim, 
and  larger. 

{h.)  Prick  a  smooth  hole  in  a  card  with  a  needle,  arrange  the 
needle  at  the  proper  distance  to  obtain  the  previous  diffusion  eff'ect, 
and  now  introduce  the  card  between  the  needle  and  the  eye, 
bringing  the  card  near  the  eye,  and  looking  through  the  hole  in  the 
card.  The  needle  will  appear  distinct  and  larger ;  it  is  distinct 
because  the  diffusion  circles  are  cut  off,  and  larger  because  the 
object  is  nearer  the  eye. 


330  PRACTICAL   PHYSIOLOGY.  [LXXI. 

(''•.)  In  a  dark  room  place  a  lighted  candle  or  gas-bnrHer  con- 
veniently, and  by  means  of  a  convex  lens  focus  the  image  of  the 
flame  on  a  sheet  of  white  paper.  It  is  better  to  introduce  a 
blackened  cardboard  screen  with  a  narrow  hole  in  it  between  the 
light  and  the  lens.  Observe  that  a  sharp  image  is  obtained  only 
at  a  certain  distance  from  the  lens.  If  the  white  screen  be  nearer 
or  farther  away,  the  image  is  blurred. 

3.  Spherical  Aberration. 

jNIake  a  hole  in  a  blackened  piece  of  cardboard  with  a  needle, 
look  at  a  light  placed  at  a  greater  distance  than  the  normal  distance 
of  accommodation.  One  will  see  a  radiate  figure,  with  four  to 
eight  radii.  The  figures  obtained  from  opposite  eyes  will  probably 
differ  in  shape. 

4.  Chromatic  Aberration. — Coloured  Fringes. 

(a.)  With  one  eye  fix  steadily  the  limit  between  a  white  and 
black  surface  (e.g.,  fig.  265),  and  while  doing  so  bring  an  opaque  card 
between  this  eye  and  the  object  (the  other  eye  being  closed),  I^t 
the  edge  of  the  card  be  parallel  to  the  limit  between  the  white  and 
black  surfaces,  so  as  to  cover  the  larger  part  of  the  pupil.  The 
margin  next  the  black  appears  with  a  yellowish-red  fringe  when 
the  part  of  the  pupil  which  lies  next  the  black  surface  is  covered, 
while  there  is  a  bluish-violet  fringe  in  the  opposite  condition. 

(b.)  Make  a  pin-hole  in  a  blackened  card,  and  behind  the  hole 
place  a  cobalt  glass.  Look  at  a  gas-flame  through  this  arrangement. 
The  cobalt  glass  allows  only  the  red  and  violet  rays  to  pass  through 
it.  Accommodate  for  the  violet  rays  or  approach  the  light,  the 
flame  appears  violet,  surrounded  with  a  reddish  halo ;  on  accommo- 
dating for  the  red,  or  on  receding,  the  centre  is  reddish  with  a 
violet  halo. 

(c.)  Place  a  strip  of  red  paper  and  one  of  blue  on  a  black  surface. 
The  red  appears  nearer  than  the  blue,  because  one  makes  a  greater 
effort  to  accommodate  for  the  less  refrangible  red  rays  than  for  the 
more  refrangible  blue  or  violet,  and  hence  the  red  is  judged  to  be 


{d.)  V.  Bezold's  Experiment. — Make  a  series  (10-12)  ot  concentric  circles, 
black  and  white  alternately,  each  i  mm.  thick,  the  diameter  of  the  whole 
being  about  1 5  mm.  On  looking  at  these  circles  when  they  are  placed  within 
the  focal  distance,  one  sees  the  white  become  pink  ;  to  some  eyes  it  a])pears 
yellow  or  greenish.  The  same  is  seen  on  looking  at  concentric  black  and 
white  circles,  or  parallel  black  and  white  lines  from  a  distance  outside  the  far 
point  of  vision  ;  the  white  appears  red  and  the  black  bluish. 

{e. )  Wheatstone's  Fluttering  Hearts. — (i. )  Make  a  drawing  of  a  red-coloured 
heart  on  a  bright  blue  ground.  In  a  dark  room  lighted  by  a  candle  hold  the 
picture  below  the  level  of  the  eyes,  and  give  it  a  gentle  to  and  fro  motion. 


LXXI.]  ACCOMMODATION.  331 

On  continuing  to  look  at  the  hearts,  it  will  appear  to  move  or  flutter  over 
the  blue  background. 

(ii.)  On  a  bright  blue  ground  make  a  square  with  black  lines  and  subdivide 
it  into  smaller  squares.  On  the  same  ground  make  a  series  of  small  squares  — 
not  coinciding  with  the  previous  ones— with  red  boundaries.  On  moving 
the  figure  to  and  fro  in  the  shade  below  the  level  of  one's  eyes,  one  sees  the  red 
squares  moving  to  and  fro  over  the  black  ones.  Some  see  the  black  moving 
behind  the  red.  ("  Zur  Erklarung  d.  flatternden  Herzen,"  A.  Szili,  Da  Hois 
Archlv,  1891,  p.  157.) 

5.  Accommodation. 

(a.)  Standing  near  a  source  of  light,  close  one  eye,  hold  up  both 
forefingers  not  quite  in  a  line,  keeping  one  fiiiger  about  six  or  seven 
inches  from  the  other  eye,  and  the  other  forefinger  about  sixteen 
to  eighteen  inches  from'  the  eye.  Look  at  the  Uf^ar  finger ;  a 
distinct  image  is  obtained  of  it,  while  the  far  one  is  blurred  or 
indistinct.  Look  at  the  far  image ;  it  becomes  distinct,  while  the 
near  one  becomes  blurred.  Observe  that  in  accommodating  for  the 
near  object  one  is  conscious  of  a  distinct  effort. 

(b.)  Ask  some  one  to  note  the  diameter  of  your  pupil  Avhen  you 
accommodate  for  the  near  and  distant  object  respectively.  In  the 
former  case  the  pupil  contracts,  in  the  latter  it  dilates.  Ask  a 
person  to  accommodate  for  a  distant  object,  and  look  at  his  eye 
from  the  side  and  somewhat  from  behind ;  the  half  of  the  pupil 
projects  beyond  the  margin  of  the  cornea.  When  he  looks  at  a 
near  object  in  the  same  line,  and  without  moving  the  eyeball, 
observe  that  the  whole  pupil  and  a  part  of  the  iris  next  the  observer 
are  projected  forwards,  owing  to  the  increased  curvature  of  the 
anterior  surface  of  the  lens. 

(c.)  Hold  a  thin  wooden  rod  or  pencil  about  a  foot  from  the  eyes, 
and  look  at  a  distant  object.  Note  that  the  object  appears  double. 
Close  the  right  eye ;  the  left  image  disappears,  and  nice  versd. 

{(l.)  At  a  distance  of  six  inches  from  the  eyes  hold  a  veil  or  thin  gauze  in 
front  of  some  printed  matter  placed  at  a  distance  of  two  feet  or  thereby.  Close 
one  eye,  and  with  the  other  one  soon  sees  either  the  letters  distinctly  or  the 
fine  threads  of  the  veil,  but  one  cannot  see  both  equally  distinct  at  the  same 
time.  The  eye,  therefore,  can  form  a  distinct  image  of  a  near  or  distant  object, 
but  not  of  both  at  the  same  time  ;  hence  the  necessity  for  accommodation. 

6.  Scheiner's  Experiment  (fig.  249). 

(a.)  Prick  two  smooth  holes  in  a  card  at  a  distance  from  each 
other  less  than  the  diameter  of  the  pupil.  Fix  two  long  fine 
needles  or  straws  in  two  pieces  of  wood  or  cork.  Fix  the  card- 
board in  a  piece  of  wood  with  a  groove  made  in  it  with  a  fine  saw, 
and  see  that  the  holes  are  horizontal.  Place  the  needles  in  line 
with  the  holes,  the  one  about  eight  inches  and  the  other  about 
eighteen  inches  from  the  card. 


332 


PRACTICAL  PHYSIOLOGY. 


[lxxi. 


(/>.)  Close  one  eye,  and  with  the  other  look  through  the  lioles  at 
the  near  needle,  which  will  he  seen  distinctly,  while  the  far  needle 
will  be  double,  but  both  images  are  somewhat  dim. 

(c.)  With  another  card,  while  accommodating  for  the  near  needle, 

close  the  right-hand  hole ; 
l>  1^  the  right-hand  image  dis- 

appears; and  if  the  left- 
hand  hole  be  closed,  the 
left-hand  image  dis- 
appears. 

(d.)  Accommodate  for 
the  far  needle ;  the  near 
needle  appears  double. 
Close  the  right-hand  hole, 
and  the  left-hand  image 
disappears;  and  on  clos- 
ing the  left-hand  hole, 
the  right-hand  image  dis- 
appears. 

{e. )  Instead  of  using  a  card 
K  perforated  with  two  holes,  use 
an  apparatus  so  constructed 
that  one  hole  is  covered  with 
a  green  and  the  other  with  a 
red  glass.  Repeat  the  pre- 
vious observations,  noting  the 
disappearance  of  the  red  or 
green  image,  as  the  case  may 
be. 

(/.)  If  desired,   the  holes 
in  the  card  may  be  made  one 
above  the  other,  but  in  this 
case  the  pin  looked  at  must  be  horizontal. 

{g.)  Make  three  holes  in  a  piece  of  cardboard,  as  in  fig.  250,  a,  so  that  they 
can  be  brought  simultaneously  before  one  eye,  and  look  at  a  pin  or  needle. 
One  sees  three  images  of  the  needle.  On  looking  at  a  near  object,  the  needles 
are  in  the  position  h,  and  at  a  distant  object  in  that  shown  in  c. 

{h.)  Miles'  Experiment. 
~  (i.)  Look  at  a   pin  through 

[a  pin-hole  in  a  card.  Ac- 
commodate for  the  pin,  move 
the  card  to  and  ho,  and  note 
that  the  pin  appear?  immov- 
able. 

(ii.)     Accommodate     for    a 
distant  object  beyond  the  pin, 
and  note  that  the  pin  appears  to  move  in  the  opposite  direction  to  that  of 
the  card. 

(iii.)  Accommodate  for  a  nearer  object,  and  note  that  the  pin  appears  to 
move  in  the  same  direction  as  the  card. 


Fia.  249.— Scheiner's  Experiment. 


Ill 


Fio.  25a 


lxxl]  accommodation.  333 

7.  Determination  of  Near  and  Far  Points. 

(a.)  Hold  a  pin  vertically  about  ten  inches  in  front  of  one  eye, 
the  other  eye  being  closed.  Look  through  the  two  holes  in  the  card 
used  for  Scheiner's  experiment,  and  when  one  distinct  image  of  the 
needle  is  seen,  gradually  approximate  the  needle  to  the  cardboard ; 
observe  that  it  becomes  double  at  a  certain  distance  from  the  eye. 
This  indicates  the  near  point  of  accommodation. 

(b.)  Hold  the  card  in  front  of  one  eye,  and  gradually  walk  back- 
wards while  looking  at  the  needle,  observing  when  it  becomes 
double.  This  indicates  the  far  point  of  accommodation.  N.B.^ 
The  experiment  (6.)  succeeds  best  in  short-sighted  individuals. 

(c.)  Determine  the  near  point  with  a  vertical  needle  and  card  with  hori- 
zontal holes,  and  again  with  a  horizontal  needle  and  a  card  with  the  holes 
vertical.  The  two  measurements  do  not  usually  coincide,  because  the  curva- 
ture of  the  cornea  is  usually  different  in  the  two  meridians. 

8.  Purkinje-Sanson's  Images. 

(a.)  In  a  dark  room  Hght  a  candle,  and  hold  it  to  one  side  of  the. 
observed  eye  and  on  a  level  with  it.  Ask  the  person  to  accommo- 
date for  a  distant  object,  and  look  into  his  eye  from  the  side 
opposite  to  the  candle,  and  three  reflected  images  will  be  seen.  At 
the  margin  of  the  pupil,  and  superficially,  one  sees  a  small  bright 
erect  image  of  the  candle-flame  reflected  from  the  anterior  svrface 
of  the  cornea.  In  the  middle  of  the  pupil  there  is  a  second  less 
brilliant,  larger,  and  not  sharply  defined  ei-eet  image.  It  is  reflected 
from  the  anterior  surface  of  the  lens.  The  third  image,  which  lies 
most  posteriorly  and  towards  the  opposite  margin  of  the  pupil,  is 
the  smallest  of  the  three,  and  is  an  inverted  image  reflected  from 
the  pof^ierior  surface  of  the  hns.  Ask  the  person  to  accommodate 
for  a  near  object,  and  observe  that  the  pupil  contracts,  while  the 
middle  image— that  from  the  anterior  surface  of  the  lens — becomes 
smaller  and  comes  nearer  to  the  corneal  image.  This  shows  that 
the  anterior  surface  of  the  lens  becomes  more  convex  during 
accommodation. 

{h.)  Instead  of  using  a  candle-flame,  cut  two  small  square  holes  (lo  mm. 
square)  in  a  piece  of  cardboard,  and  behind  each  place  a  gas-flame,  and  observe 
the  three  pairs  of  square  reflected  images. 

(f.)  Physical  Experiment.— Place  in  a  convenient  position  on  a  table  a  large 
biconvex  lens,  supported  on  a  stand.  Standing  in  front  of  it,  hold  a  watch- 
glass  in  the  left  hand  in  front  of  the  lens  and  a  few  inches  from  it.  Move  a 
lighted  candle  at  the  side  of  this  arrangement,  and  observe  the  three  images 
described  above.  Substitute  a  convex  lens  of  shorter  focus,  and  observe  how 
the  images  reflected  from  the  lens  become  smaller. 

9.  The  Phakoscope  of  Helmholtz  is  used  to  demonstrate  the 


334 


PRACTICAL  PHYSIOLOGY. 


[lxxl 


change  in  curvature  of  the  lens,  more  especially  of   the  anterioi 
surface,  during  accommodation  (fig.  251). 

(a.)  Place  the  phakoscope  in  a  convenient  position,  and  darken  the  room. 
Two  persons  are  required.  The  observed  eye  (patient)  looks  through  a  hole  in 
the  box  opposite  to  c,  while  the  observer  looks  through  the  hole  {a)  at  the  side. 
Light  a  lamp,  place  it  some  distance  from  the  two  prisms  {h,  b')  in  such  a 
position  that  its  liglit  is  thrown  clearly  upon  the  pbserved  eye,  and  the 
observer  sees  two  small  bright  square  images  of  light,  when  the  observed  eye 
looks  straight  ahead  at  a  distant  object.  These  are  the  corneal  images.  He 
should  also  see  in  the  observed  eye  two  larger  less  distinct  images,  from  the 
anterim-  surfoA^e  of  the  lens^  and  two  smaller  much  dimmer  images,  from  the 
posterior  surface  of  tfie  lens.     The  last  are  seen  with  diflficulty. 

(b.)  Ask  the  patient  to  accommodate  for  a  near  object,  viz.,  the  pin  above  c, 
keeping  the  eye  unmoved.  Observe  that  the  middle  image  becomes  smaller 
and  goes  nearer  to  the  corneal  one,  while  the  other  two  undergo  no  perceptible 
change.     At  the  same  time  the  pupil  becomes  smaller. 


FlO.  asT.— Phakoscope.  a.  Hole  for  observer's 
eye  ;  b,  b'.  Prisms ;  c.  Carries  a  pin  for 
the  observed  eye  to  fix  as  its  near  point. 


Fig.  252.— Anber's  Model  to  show 
the  principle  of  the  Ophthal- 
mometer. 


10.  Principle  of  Helmholtz's  Ophthalmometer.— The  student  may  con- 
veniently learn  the  principle  of  this  instrument  ft*om  the  apparatus  of  Auber 
(fig.  252)  (made  by  Petzold  of  Leipzig).  By  means  of  the  ophthalmometer 
Helmholtz  measured  the  size  of  Sanson's  images  and  tlie  changes  in  size  during 
accommodation.  If  one  looks  at  an  object  through  a  plate  of  glass  in  a  direc- 
tion at  right  angles  to  the  surface  of  the  glass,  the  object  is  seen  single  and  in 
its  exact  position.  If,  however,  one  looks  at  it  obliquely  or  displaces  the  glass, 
then  the  image  appears  displaced  to  the  right  or  left  according  to  the  inclina- 
tion of  the  glass  plate.     In  Helmholtz's  instrument  two  glass  plates,  as  in  fig. 


LXXI.]  ACCOMMODATION.  335 

252,  were  placed  one  above  the  other,  and  could  be  rotated  in  opposite  directions 
round  a  vertical  axis.  One  looks  through  the  glass  plates  at  two  black  lines 
painted  on  a  sheet  of  glass.  On  looking  at  the  two  lines  through  the  two  glass 
plates,  and  on  rotating  the  latter  in  opposite  directions,  one  image  is  displaced 
to  the  right  and  the  other  to  the  left,  and  the  object  appears  double.  One  rotates 
the  plates  until  the  inner  edge  of  the  one  image  coincides  with  the  correspond- 
ing edge  of  the  other,  so  that  each  image  has  been  disjjlaced  exactly  to  the  extent 
of  the  size  of  the  object.  The  size  of  the  image  can  be  calculated,  provided  one 
knows  the  refractive  index  of  the  glass  plates,  their  thickness,  and  the  angle 
formed  by  them.  In  the  ophthalmometer  the  extent  of  rotation  is  read  olf  on 
a  disc  placed  outside  the  box  which  contains  the  glass  plates. 

11.  Line  of  Accommodation,  z.e.,  the  eye  does  not  accommodate 
for  a  point,  but  for  a  series  of  points,  all  of  wliich  are  equally 
sharply  perceived  with  a  certain  accommodation. 

(a.)  Stretch  a  white  thread  about  a  metre  long  on  a  blackened  wooden 
board.  Through  two  narrow  slits,  about  2  mm.  apart,  in  a  blackened  card, 
focus  with  one  eye  a  particular  part  of  the  thread,  which  must  be  in  the  optic 
axis.  A  part  of  the  thread  on  the  far  and  near  side  of  the  point  tocussed  is 
quite  distinct  and  linear,  but  beyond  or  nearer  than  this  the  thread  is  double, 
and  diverges  from  the  point  focussed. 

{b. )  Make  a  small  black  spot  with  ink  on  a  glass  plate,  and  hold  it  in  front 
of  any  printed  matter.  Bring  the  eye  as  close  as  possible  to  the  glass  plate 
without  losing  distinct  definition  of  the  point.  At  one  and  the  same  time 
only  one  of  the  objects  can  be  seen  ;  but  not  the  point  and  the  print  equally 
sharply  defined.  Remove  the  eye  gradually  from  the  glass  plate,  and  ulti- 
mately at  a  certain  distance  both  the  point  and  print  will  be  equally  distinct  ; 
the  point  and  print  mark  the  extreme  limits  of  the  line  of  accommodation. 

12.  Astigmatism  is  usually  due  to  unequal  curvatures  of  the  cornea 
in  different  meridians,  i.e.y  the  surface  of  the  cornea  is  not  part  of 
a  perfect  sphere.  Astigmatism  is  not  uncommon,  and  usually  the 
curvature  of  the  cornea  is  greater  in  the  vertical  than  in  the  hori- 
zontal meridian.  This  is  "regular  astigmatism."  In  such  a 
"  spoon-shaped  "  cornea  a  point  of  light  is  not  focussed  as  a  point — 
"  pin  focus,"  but  is  linear  or  "  line  focus." 

(a.)  Draw  on  a  card  two  black  lines  of  equal  thickness,  intersect- 
ing each  other  at  right  angles.  Fix  it  vertically  at  the  far  limit  of 
accommodation  and  look  at  it,  when  probably  either  the  vertical  or 
the  horizontal  line  will  be  seen  more  distinctly.  Test  each  eye 
separately.  The  line  most  distinct  corresponds  to  the  meridian  of 
least  curvature  of  the  cornea. 

{h.)  Instead  of  a  cross,  construct  a  star,  the  lines  radiating  at  equal  angles 
from  the  centre,  and  being  of  equal  thickness.  Repeat  the  previous  observa- 
tions, observing  in  which  meridian  the  lines  are  most  distinct. 

(c.)  Repeat  these  observations  with  the  "astigmatic  clock"  suspended  on 
the  wall,  or  with  ap})ropriate  illustrations  given  in  SnellnCs  "Test-types." 

{(i.)  Construct  a  series  of  concentric  circles  of  equal  thickness  and  tint, 
about  one-eighth  of  an  inch  apart  upon  a  card.  Make  a  small  hole  in  the 
centre  of  the  card.     Look  steadily  at  the  centre  of  the  card  held  at  some 


336  PRACTICAL  PHYSIOLOGY.  [LXXI. 

distance.  All  the  parts  will  not  be  equally  distinct.  Approach  the  card 
towards  you,  noting  in  which  diameter  the  lines  appear  most  distinct. 

{e. )  This  card  may  be  used  in  another  way.  Hold  the  card  in  front  of,  and 
with  the  circles  directed  towards  the  eye  of  another  person — especially  one 
with  astigmatism  ;  place  your  own  eye  behind  the  hole  in  the  card  and  look 
into  the  observed  eye,  noting  the  reflection  of  the  circles  to  be  seen  in  the  eye. 
Observe  in  which  meridian  the  circles  are  most  distinct,  and  if  there  be  any 
perceptible  difference  in  the  thickness  and  distinctness  of  the  circles. 

(/,)  Draw  a  series  of  parallel,  vertical,  and  horizontal  lines  of  equal  tint  and 
thickness,  and  about  one-eighth  of  an  inch  apart.  Fix  the  card  vertically  at 
a  distance,  and  move  towards  it,  noting  whether  the  vertical  or  horizontal 
lines  are  most  distinct. 

(g.)  Fix  a  fine  wire  or  needle  vertically  in  a  piece  of  wood  moving  in  a  slot, 
and  similarly  fix  another  needle  or  wire  horizontally.  Move  the  needles 
until  both  can  be  seen  distinctly  at  the  same  time,  when  it  will  be  found  that 
the  needles  are  some  distance  apart ;  usually  the  horizontal  one  is  the  nearer. 

13.  Diplopia  Monophthabnica. 

^lake  a  small  hole  in  a  black  card,  hold  it  at  some  distance,  and  with  one  eye 
look  through  it  at  a  luminous  point,  the  eye  being  accommodated  for  a  distant 
object.  One  sees  either  several  objects  (feeble  light)  or  an  irregular  radiate 
figure  with  four  or  eight  rays.  Move  the  paper,  and  the  long  rays  remain  in 
the  same  position.  Compare  the  figure  obtai.ied  from  the  other  eye.  It  will 
very  likely  be  difi"erent, 

14.  Movements  of  Iris.— (i.)  It  is  an  extremely  beautiful  experi- 
ment, and  one  that  can  easily  be  made  by  looking  at  the  white  shade 
of  an  ordinary  reading-lamp,  to  look  through  a  pin-hole  in  a  card  at  a 
uniform  white  surface.  With  the  right  eye  look  through  the  pin- 
hole, the  left  eye  being  closed.  Note  the  size  of  the  (slightly  dull) 
circular  visual  field.  Open  the  left  eye,  the  field  becomes  brighter 
and  smaller  (contraction  of  pupil),  close  the  left  eye,  after  an 
appreciable  time,  the  field  (now  slightly  dull)  is  seen  gradually  to 
expand.  One  can  thus  see  and  observe  the  rate  of  movements  of 
one's  own  iris. 

(ii.)  Pupil-Reflex. 

Place  a  person  in  front  of  a  bright  light  opposite  a  window,  and 
let  him  look  at  the  light,  or  place  oneself  opposite  a  well-illuminated 
mirror.  Close  one  eye  with  the  hand  and  observe  the  diameter  of 
the  other  pupil.  Then  suddenly  remove  the  hand  from  the  closed 
eyp.  ]\crht  falls  upon  it;  at  the  same  time,  the  pupil  of  the  other  eye 
contracts. 

15.  Pupil  of  Albino  Rabbit.— The  pupil  in  albinos  appears  red, 
although  in  other  animals  it  is  black.  In  the  albino  it  is  red  owing 
to  the  absence  of  pigment  in  the  choroid  and  iris,  so  that  light  is 
admitted  through  the  sclerotic  and  choroid  and  is  reflected  from 
the  interior  of  the  eyeball  through  the  pupil  to  the  eye  of  the 
observer. 


LXXII.]  BLIND   SPOT.  337 

Place  in  front  of  the  eye  of  an  albino  rabbit  a  black  screen  with  a  hole  in 
it  of  exactly  the  same  size  as  the  pupil.  Let  the  hole  and  pupil  correspond 
in  position  to  each  other.  The  pupil  then  appears  black,  as  the  card  arrests 
the  lateral  rays  that  fall  upon  the  eyeball. 

16.  The  Pupil  Appears  Larger  than  it  is  in  Reality. 

To  see  the  pupil  at  its  exact  size,  an  excised  eyeball  must  be  observed  in 
water.  If  a  glass  model  of  a  pupil  be  taken,  and  then  be  covered  l.y  an- 
other thick  concavo-convex  glass  in  shape  like  the  cornea,  the  pupil  at  once 
appears  larger. 

17.  Lud wig's  Apparatus  for  Vision  of  a  Point. 

The  black  plate  (fig.  253)  is  fixed  in  the  slot  so  that  either  a  slit  or  a  hole 
is  just  above  the  handle  of  the  instrument.  Remove  from  the  instrument 
the  carrier  with  the  steel  point,  and  on  tlie 
bar  of  the  instrument  place  the  vertical 
slit  of  the  black  plate  (visual)  near  the 
eye.  There  is  a  movable  black  j)late  witli 
a  small  hole  in  it.  On  looking  at  this 
small  hole  through  a  vertical  slit  it  appears 
oval  from  above  downwards,  while  with 
a  horizontal  slit  the  round  hole  appears 
drawn  out  laterally.  If  there  be  two  small 
holes  near  each  other  in  the  visual  plate, 
then  at  a  certain  distance  two  are  seen  in 
the  movable  plate.  If  the  m.ovable  plate 
be  removed,  and  the  steel  point  put  in  its 
j.lace,  on  using  the  large  hole  in  the  visual  ^^^-  253--;''.'dwig'8  Apparatus  for 
plate,  and  bringing  the  steel  point  towards  ^'''*'"  ""^  *  ^'''"^• 

the  eye,  after  a  time  one  ceases  to  see  it 

distinctly,  or  if  seen  it  is  blurred.     On  using  the  small  hole  in  the  visual 
plate,  the  rod  appears  distinct  (fig.  253). 

18.  Listing's  Reduced  Eye. — The  various  dioptric  media  of  the  eye  may  be 
considered  as  equal  to  a  single  substance  with  a  refractive  index  of  1.35  and 
a  single  spherical  surface  of  radius  5.1248  mm.  The  position  cf  the  nodal 
point  is  5  mm.  behind  the  refit-active  surface,  and  the  i)rincipal  focus  1 5  mm. 
behind  this.  This  latter  value  is  of  special  importance  in  enabling  one  to 
calculate  the  size  of  a  retinal  image — the  size  and  distance  of  the  object  being 
known. 


LESSON  LXXII. 


BLIND  SPOT  — FOVEA  CENTRALIS  —  DIRECT 
VISION— CLERK-MAXWELL'S  EXPERIMENT— 
PHOSPHENES— RETINAL  SHADOWS. 

1.  The  Blind  Spot. 

(a.)  Mamotte's  Experiment. — As  in  fig.  254,  on  a  white  card, 
make  a  cross  and  a  large  dot,  either  black  or  coloured.  Hold  the 
card  vertically  about  10  inches  from  the  right  eye,  the  left  bein^j 


338 


PRACTICAL   PHYSIOLOGY. 


[lxxil 


closed.  Look  steadily  at  the  cross  with  the  right  eye,  when  both  the 
cross  and  the  circle  will  be  seen.  Gradually  approach  the  card 
towards  the  eye,  keeping  the  axis  of  vision  fixed  on  the  cross.  At  a 
certam  distance  the  circle  will  disappear,  i.e.,  when  its  image  falls  on 


fitf.  854.— Marriotte's  Experiment. 

the  entrance  of  the  optic  nerve.     On  bringing  the  card  nearer,  the 
circle  reappears,  the  cross  of  course  being  visible  all  the  time. 

(b. )  Perform  the  experiment  in  this  way.  Place  the  flat  hand  vertical  to 
the  face,  and  with  its  edge  touching  the  nose  so  as  to  form  a  septum  between 
the  two  fields  of  vision.     Fix  the  cross  in  fig.  255,  keej^  buth  eyes  open,  and 


+ 


FlO.  255. 


on  moving  the  paper  to  and  fro  at  a  certain  distance  both  black  dots  will 
disappear. 

(c. )  Close  the  left  eye,  and  fix  the  point  a  (fig.  256)  ;  on  moving  the  paper  a 
certain  distance  (about  16  cm. ),  one  sees  a  complete  cross,  and  to  most  obserrers 
the  horizontal  bar  appears  uppermost. 


a 
+ 


Fio.  256 


(rf.)  Volkmann*8  Experiment  on  the  Blind  Spot. 

Look  at  the  spot  a  (fig.  257)  with  one  eye,  the  gap,  b  c,  disappears  when  it 
falls  on  the  blind  spot  and  the  line  looks  continuous  ;  the  points  b  and  c  appear 
as  it  placed  in  the  same  point  of  the  field  of  vision,  so  that  the  parts  of  the 


LXXII.]  DIRECT  VISION.  339 

retina  in   the  peripliery  of  the  blind  spot  behave  as  if  two  diametrically 
opposite  points  approached  each  other. 

2.  Map  out  the  Blind  Spot. 

Make  a  cross  on  the  centre  of  a  sheet  of  white  paper,  and  place  it  on 
a  table  about  lo  or  12  inches  from  you.  Close  the  left  eye,  and  look 
steadily  at  the  cross  with  the  right.  Wrap  a  penholder  in  white  paper, 
leaving  only  the  tip  of  the  pen-point  projecting  ;  dip  the  latter  in  ink,  or  dip 
the  point  of  a  white  feather  in  ink,  and  keeping  the  head  steady  and  the  axis 
of  vision  fixed,  place  the  pen-point  near  the  cross,  and  gradually  move  it  to 


I  I- 


b  c 

Fig.  957.— Volkmann's  Experiment  on  the  Blind  Spot. 

the  right  until  the  black  becomes  invisible.  Mark  this  spot.  Carry  the 
blackened  point  still  farther  outwards  until  it  becomes  visible  again.  Mark 
this  outer  limit.  These  two  points  give  the  outer  and  inner  limits  of  the 
blind  spot.  Begin  again,  moving  the  pencil  first  in  an  upward  and  then  in  a 
downward  direction,  in  each  case  marking  where  the  pencil  becomes  invisible. 
If  this  be  done  in  several  diameters,  an  outline  of  the  blind  spot  is  obtained, 
even  little  prominences  showing  the  retinal  vessels  being  indicated. 

3.  Calculate  the  Size  of  the  Blind  Spot. 

Helmhaltz  gives  the  following  formula  for  this  purpose : — When  /  is  the 
distance  of  the  eye  from  the  paper,  F  the  distance  of  the  second  nodal 
point  from  the  retina — usually  15  mm.  — c?  the  diameter  of  the  sketch  of  the 
blind  si)ot  drawn  on  the  paper,  and  D  the  corresponding  size  of  the  blind 
spot  :— 

/        ^. 
F  '''  D 

4.  Acuity  of  Vision  of  the  Fovea  Centralis. 

{a.)  On  a  horizontal  plane— a  blackboard — describe  a  semicircle  with  a 
radius  equal  to  that  of  the  near  point  of  vision,  and  fix  in  the  semicircle  pins 
it  an  angular  distance  of  5°  apart.  Close  one  eye,  and  with  the  other  look  at 
khe  central  pin  ;  the  pins  on  each  side  will  be  seen  distinctly  ;  those  at  10° 
begin  to  be  indistinct,  while  those  at  30°  to  40''  are  not  seen  at  all. 

(6.)  At  a  distance  of  5  feet  look  at  a  series  of  vertical  parallel  lines  alter- 
nately black  and  white,  each  .5  mm.  wide.  A  normal  eye  will  distinguish 
ihem  ;  if  not,  approach  the  object  until  they  are  seen  distinctly. 

5,  Dii'ect  Vision. — When  the  image  of  an  object  falls  on  the 
lovca  centralis,  we  have  "  direct  vision."  "When  it  falls  on  any 
3ther  part  of  the  retina,  it  is  called  "  indirect  vision."  Vision  is 
<nost  acute  at  the  fovea  centralis  of  the  yellow  spot. 

(a.)  Standing  about  2  feet  from  a  wall,  hold  up  a  pen  at  arm's 
length  between  you  and  the  wall.  Look  steadily  at  a  fixed  spot 
on  the  wall,  seeing  the  pen  distinctly  all  the  time.  Move  the  pen 
gradually  to  one  side ;  first  one  fails  to  see  the  hole  in  the  nib,  and 
as  the  pen  is  carried  outwards  one  fails  to  recognise  it  as  a  pen. 


340 


PRACTICAL  PHYSIOLOGY. 


[lxxil 


Hence,  in  looking  at  a  large  surface,  to  see  it  distinctly  one  must 
unconsciously  move  his  eyeballs  over  the  surface  to  get  a  distinct 
impression  thereof. 

{b.)  Make  two  black  dots  on  a  card  quite  close  together,  so  that  when 
looked  at  they  are  seen  as  two.  Hold  up  the  left  index-finger,  look  steadily 
at  it,  and  place  the  card  with  the  dots  beside  the  finger.  Move  the  card  out- 
wards, inwards,  upwards,  and  downwards  successively,  and  note  that  as  the 
dots  are  moved  towards  the  periphery  they  appear  as  one,  but  not  at  equal 
distances  from  the  fixed  point  in  all  meridians.  For  convenience,  the  card 
may  be  moved  along  a  rod,  movable  on  a  vertical  support. 

6.  Clerk-Maxwell's  Experiment — The  Yellow  Spot. 

A  strong,  watery,  clear  solution  of  chrome  alum  is  placed  in  a 
clear  glass  bottle  with  flat  sides.  Close  the  eyes  for  a  minute  or 
so,  open  them,  and,  while  holding  the  chrome  alum  solution  between 
one  eye  and  a  white  cloud,  look  through  the  solution.  An  elliptical 
spot,  rosy  in  colour,  will  be  seen  in  the  otherwise  green  field  of 
vision.  The  pigment  in  the  yellow  spot  absorbs  the  blue-green 
rays,  hence  the  remaining  rays  which  pass  through  the  chrome  alum 
give  a  rose  colour. 


\ 


7.  Bergmann's  Experiment. — Make  a  series  of  parallel  vertical 

black  lines,  2  mm.  in  diameter,  on  white  paper,  with  equal  white 

areas  intervening  between  them.     Look  at  them  in  a  good  light, 

at  a  distance  of    2  to  3  yards. 

In  a  short   time   the  lines  will 

appear  as  in  fig.  258,  A.     Why? 

Because  of  the  manner  in  which 

the  images  of   the  lines  fall  on 

the  cones  in  the  yellow  spot,  as 

.       shown  in  B. 

II 

8.  Phosphenes. 

Press  the  tip  of  the  finger 
firmly,  or  the  end  of  a  pencil, 
against  the  inner  corner  of  the 
closed  eye.  A  brilliant  circular  patch,  with  a  steel-grey  centre 
and  yellow  circumference,  is  seen  in  thejidd  of  vision  and  on  the 
opposite  side.  It  has  the  same  shape  as  the  compressing  body. 
Press  any  other  part  of  the  eyeball ;  the  same  spectrum  is  seen, 
and  always  on  the  opposite  side.  Impressions  made  on  the 
terminations  of  the  optic  nerve  are  referred  outside  the  eye,  i.e., 
beyond  into  space.  The  phosphene  is  seen  in  the  upper  half  if 
the  lower  is  pressed,  and  vice  versd. 


FIQ.  358.— i>ergmann's  Experiment. 


LXXTI.]  DIRECT  VISION.  34 1 

9.  Shadows  of  the  Fovea  Centralis  and  Retinal  Blood-Vessels. 

Move,  with  a  circuLar  motion,  a  blackened  card  with  a  pin-hole 
in  its  centre  in  front  of  one  eye,  looking  through  the  pin-hole 
at  a  white  cloud.  Soon  a  punctated  field  appears  with  the  out- 
lines of  the  capillaries  of  the  retina.  The  oval  shape  of  the  yellow 
spot  is  also  seen,  and  it  will  be  noticed  that  the  blood-vessels  do 
not  enter  the  fovea  centralis.  Move  the  card  vertically,  when  the 
horizontal  vessels  are  more  distinct.  On  moving  it  horizontally, 
the  vertical  ones  are  most  distinct.  Some  observers  recommend 
that  a  slip  of  blue  glass  be  held  behind  the  hole  in  the  opaque  card ; 
but  this  is  unnecessary. 

10.  Purkinje's  Figures, 

In  a  dark  room  light  a  candle,  and  ^tand  in  front  of  a  mono- 
chromatic wall.  If  this  is  not  available,  hang  up  a  large  white 
sheet,  and  while  looking  steadily  with  one  eye  towards  the  wall 
or  sheet,  accommodating  the  eye  for  a  distant  object,  hold  the 
candle  close  to  the  side  of  that  eye,  well  out  of  the  field  of  vision, 
— downwards  and  laterally  from  the  eye, — and  move  the  candle  up 
and  down.  It  is  better  to  direct  the  eye  outwards,  keeping  it 
accommodated  for  a  distant  object.  Ere  long,  dark  somewhat  red- 
brown  branching  lines,  shadows  of  the  retinal  vessels,  will  be  seen 
on  a  red  background,  due  to  the  shadows  cast  by  the  retinal 
vessels  on  the  percipient  parts  of  the  retina.  Therefore  the  parts 
of  the  retina  stimulated  by  light  must  lie  behind  the  retinal  blood- 
vessels. If  the  candle  be  moved  in  a  vertical  plane,  the  shadows 
move  upwards  or  downwards  with  the  hght.  If  the  light  be  moved 
horizontally,  the  shadows  move  in  an  opposite  direction. 

Entoptical  Vision. — By  this  is  meant  the  visual  perception  of 
objects  situated  within  our  own  eye.  There  are  many  such 
phenomena. 

11.  MuscDB  Volitantes. 

{a.)  Light  a  caiuUe  in  a  dark  room  ;  at  a  distance  from  it  place 
a  black  screen  with  a  pin-hole  in  it.  Focus  by  means  of  a  convex 
lens  the  image  of  the  flame  upon  the  hole  in  the  screen.  Look 
through  the  hole  with  one  eye,  and  on  the  illuminated  part  of  the 
lens  will  be  seen  images  of  dots  and  threads  due  to  objects  within 
the  eyeball. 

{b.)  Rays  of  light  proceeding  from  a  point  at  or  preferably  within  the 
anterior  focus  of  the  eye.  i.e.,  13  mm.  or  less  from  the  cornea,  cast  a  shadow 
of  any  object  within  the  eyeball,  because  the  rays  fall  parallel  on  the  retina. 

Make  a  jiin-hole  in  a  card,  place  it  close  to  the  eyeball,  and  through  the  hole 
look  at  an  illuminated  surface,  e.g.,  a  white  lamp-shade,  or  white  sky.  The 
margins  of  the  aperture  become  luminous,  i.e.,  they  are  the  luminous  body. 


342  PRACTICAL   PHYSIOLOGY.  [LXXH. 

One  sees  such  floating  objects  as  are  present  in  the  media  of  one's  eye,  the 
"muscie  volitantes." 

12.  Inversion  of  Shadows  thrown  on  the  Eetina. 

Make  tliree  pin-holes  in  a  card,  and  arrange  them  in  a  triangle  close  to 
each  other.  Hold  the  card  4  or  5  inches  from  the  right  eye,  and  look 
through  the  holes  at  a  bright  sky  or  lamp.  Close  the  left  eye,  and  in  front  of 
tlie  right  hold  a  pin  so  that  it  just  touches  the  eyelashes.  An  inverted  image 
of  tlie  pin  will  be  seen  in  each  pin-hole.  Retinal  images,  as  we  have  seen,  are 
inverted  on  the  retina,  shadows  on  the  retina  are  erect,  and  therefore  the 
latter,  on  being  projected  outwards  into  space,  are  seen  inverted. 

13.  Duration  of  Impressions. 

On  a  circular  white  disc,  about  half-way  between  the  centre  and 
circumference,  fix  a  small  black  oblong  disc,  and  rapidly  rotate  it 
by  means  of  a  rotating  wheel.  Tliere  appears  a  ring  of  grey  on 
the  black,  showing  that  the  impression  on  the  retina  lasts  a  certain 
time. 

14.  Talbot's  Law. — A  grey  once  produced  is  not  changed  by  increased 
ra]>idity  of  rotation  of  the  disc  exciting  the  sensation.  The  intensity  of  the 
light  impression  is  quite  independent  of  the  absolute  duration  of  the  periods 
of  illumination  and  shade. 

Rotate  a  disc  like  fig.  259  twenty-five  times  per  second,  then  the  period 
in  which  illumination  and  shade  alternately  lasts  for  the  inner  zone  is  -^  sec, 
for  the  middle  J)j,  and  for  the  outer  zone  y^^^  sec.     In  all  three  zones  the  period 

of  illumination  lasts  exactly  one-half 
of  the  period,  and  the  three  zones 
have  exactly  the  same  brightness. 
Rotate  more  quickly,  and  no  further 
effect  is  produced.  The  number  of 
rotations  is  readily  determined  by 
Harding's  improved  counter. 

15.    Charpentier's      Experi- 
ments  (slow-moving  discs). 

(i.)  "  BlorJi-ba?id  Expei-iment" 
— Make  a  disc  \  wliite,  cause  it 
to  revolve  (once  in  two  seconds) 
in  bright  direct  sunsliine.  On 
the  white  sector  will  be  seen  a 
Fio.  259.  narrow  "  black  band  "  or  sector 

near  the  black  edge  that  has 
just  passed  in  front  of  the  eye,  but  separated  from  that  edge  by 
a  narrow  white  sector  (fig.  260).  The  black  band  always  appears 
at  the  same  time  from  the  moment  the  white  sector  appears  in  the 
field.  The  time  is  equal  to  -^j^  to  -^  second,  i.e.,  0.014"  ^  0.016". 
It  is  independent  of  the  velocity  of  the  disc.  Sometimes  there 
are  two  or  three  successive  fainter  bands,  but  they  are  difi&cult  to 
make  out. 


LXXII.] 


DIRECT  VISION. 


3*43 


The  first  effect  is  white,  followed  by  an  after-eftect  which  is  black 
even  during  the  continued  white  stimulus.  Thus  there  seems  to  be  a 
slow  oscillatory  process  in  the  retino-cerebral  apparatus,  showing  a 
positive  and  a  negative  phase,  each  phase  lasting  0.014"  to  0.016". 

The  negative  phase  of  oscillation  takes  place  after  the  shortest 
possible  illumination,  and  appears  to  be  a  general  phenomenon. 
Charpentier  suggests  that  it  is  possible  that  a  single  bright  stimulus. 
e.g.,  an  electric  spark,  appears  as  a  double  or  reduplicated  bright 
sensation  {Archives  de  Phtjsiologie,  1892,  p.  541).  Another  form 
of  the  experiment  is  given  in  a  later  paper  (p.  629). 


FlO.  260.  — Charpentier*s  Disc  for 
"Black  Band."  The  arrow 
shows  the  direction  of  rotation. 


FlO.  261.— Charpentier's  Disc  for  Vision 
of  Purple  Background. 


(ii.)  On  a  large  black  disc  (40  cm.  diameter)  gum  near  its  circumference  a 
piece  of  white  paper  (i  cm.  and  angular  deviation  i°-2°),  and  cause  the  diso 
to  revolve  twice  per  second.  The  observer  has  a  sensation  of  a  white  ribbed 
streak  (about  ^  of  the  entire  circle)  on  the  black  surface.  There  is  not  a 
uniform  tint,  and  the  ribbed  appearance  is  due  to  an  oscillatory  process  in 
the  retino-cerebral  a])paratus. 

(iii.)  Arrange  a  black  disc  with  narrow  open  equidistant  sectors,  to  rotate 
opposite  to  a  white  surface  illuminated  by  direct  sunlight.  The  sectors  have 
their  apices  towards  the  periphery  and  thf;ir  bases  it  the  centre  (fig.  261 ),  On 
rotating  tho  disc  before  the  eyes  so  that  the  retina  is  stimulated  40-60  times 
per  second,  i.e.,  when  each  stimulus  oocurs  during  the  negative  after-effect 
of  the  preceding  stimulus,  one  gets  a  sensation  of  a  purple-violet  field,  but  the 
field  is  colourless  at  lower  or  higher  rates  of  stimulation.  Charpentier  thinks 
that  the  coloured  sensation  is  due  to  entoptical  vision  of  the  retinal  purple. 


344 


PRACTICAL   PHYSIOLOGY. 


[lxxiil 


LESSON  LXXIIL 

PERIMETRY— IRRADIATION— IMPERFECT  VISUAL 
JUDGMENTS. 


1.  To  Map  out  the  Field  of  Vision,  or  Perimetry. 

('/.)  A  rough  method  is  to  place  the  person  with  his  back  to  a 
window,  ask  him  to  close  one  eye,  stand  in  front  of  him  about  2 
feet  distant,  hold  up  the  forefingers  of  both  hands  in  front  of  and 

in  the  plane  of  your  own 
face.  Ask  the  person  to 
look  steadily  at  your  nose, 
and  as  he  does  so  observe 
to  what  extent  the  fingers 
can  be  separated  horizon- 
tally, vertically,  and  in 
oblique  directions  before 
they  disappear  from  his 
field  of  vision. 

{b.)  Priestley  Smith's  Peri- 
meter  (fig.  262).— Let  the  ob- 
server seat  himself  near  a 
table  on  which  the  perimeter 
is  placed  at  a  convenient 
height.  Suppose  the  right  eye 
is  to  be  examined,  fix  a  blank 
chart  for  the  right  eye  behind 
the  wooden  circular  disc.  A 
mark  on  the  hand-wheel  shows 
which  way  the  chart  is  to  be 
l)laced. 

(('.)  The  patient  rests  his 
riglit  cheek  against  the  knob 
on  the  wooden  pillar  in  siich  a 
position  that  the  knob  is  about 
an  inch  directlj  under  his  right  eye,  the  other  eye  is  closed  either  voluntarily 
or  with  a  shade,  while  the  observer  looks  steadily  with  the  right  eye  at  the 
white  spot  on  the  end  of  the  axis  of  the  instrument. 

(d.)  The  observer  turns  the  quadrant  with  his  right  hand  by  means  of  the 
wooden  wheel,  first  to  one  and  then  to  another  meridian.  With  his  left  he 
moves  the  white  mark  along  the  quadrant,  beginning  at  the  periphery  and 
gradually  approaching  centralwards  until  it  is  just  seen  by  the  right  eye.  A 
prick  is  then  made  in  the  chart  corresponding  to  the  angle  read  off  on  the 
quadrant,  at  which  the  observer  can  see  the  white  spot. 

(e.)  Turn  the  quadrant  to  another  meridian  and  determine  the  limit  of  the 
risual  field  as  before.     This  is  repeated  for  four  or  more  meridians,  and  theo 


262.— Priestley  Smith's  Perimeter. 


LXXIII.] 


PERIMETRY,  IRRADIATION,  ETC. 


345 


the  pricks  on  the  chart  are  joined  by  a  continuous  line,  when  we  obtain  an 
oval  field  more  extensive  in  the  outer  and  lower  portions.  Test,  if  desired,  the 
left  eye,  substituting  a  blank  chart  for  that  eye. 

(/. )  Test  the  field  of  vision  for  colours,  substituting  for  the  white  travelling 
disc  blue,  red,  and  green.  Mark  each  colour-field  on  the  chart  with  a  pencil 
of  similar  colour.  Notice  that  the  field  for  blue  is  nearly  as  large  as  the 
normal  visual  field.  It  is  smallest  for  green,  red  being  intermediate  between 
green  and  blue. 

{(/.)  With  Ludwig's  apparatus  test  when  red,  yellow,  blue,  and  other 
coloured  glasses  cease  to  be  distinguished  as  such  in  the  field  of  vision. 

2.  Binocular  Vision. 

(a.)  Hold  in  front  of  each  eye  a  blackened  tube.  On  looking 
through  both  tubes  two  fields  will  be  seen.  Gradually  cause  the 
tubes  to  converge  at  their  free  ends,  and  the  two  fields  of  vision  will 
be  seen  to  meet  and  form  a  single  field. 

(b.)  Continue  the  convergence,  and  note  that  two  fields  reappear, 
but  they  are  crossed.  In  these  "  secondary  positions  "  there  is  no 
rotation  of  the  eyeball  on  its  antero-posterior  axis. 

{('.)  If  the  eyeball  be  turned  in  any  other  direction  (tertiary 
positions)  the  after-image  appears  inclined,  or  at  an  angle  with  the 
vertical  or  horizontal  stripes,  according  to  the  original  position  of 
the  red  fixation-object. 

3.  Wheel  Movements  (False)  of  the  Eyeballs  (Secondary  and  Tertiary 
Positions). 

(a.)  On  a  grey  sheet  of  stout  paper,  at  least  i  metre  square,  rule  a  number 
of  vertical  and  horizontal  faint 
black  lines.  Fix  on  the  centre  of 
the  paper  a  strip  of  red  paper  on  a 
level  with  the  eyes,  the  eyes  being 
in  the  primary  ])Osition,  i.e.,  look- 
ing straight  ahead.  Gaze  steadily 
at  the  latter,  keeping  the  head 
fixed.  After  a  time  suddenly  direct 
the  eyeballs  to  another  part  of  the 
grey  surface ;  a  green-blue  after- 
image is  seen  which  retains  its 
same  relative  position  with  regard 
to  the  vertical  and  horizontal  lines, 
provided  the  eyeballs  be  moved 
directly  upwards,  downwards,  in- 
wards, or  outwards,  i.e.,  if  the  eye- 
ball is  moved  up,  along  vertical  or 
horizontal  meridians,  the  after- 
image is  still  vertical.  Turn  the 
eyeball  upwards  and  to  the  right, 
or  downwards  and  to  the  left,  the 
head  being  kept  in  the  same  posi- 
tion, the  after-image  appears  tilted 
to  the  right  ;  if  the  eyes  are  directed 
upwards  and  to  the  left  or  downwards  and  to  the  right,  the  after-imgae  appears 
tilted  to  the  left.     A  similar  result  occurs  with  a  horizontal  strip  of  paper, 


nnnn 
maam 


FlO.  263.— Appearance  of  a  Cross  in  False 
Wheel  Movements  of  Eyeballs. 


346 


PRACTICAL  PHYSIOLOGY. 


[lxxiii. 


but  the  after-images  are  inclined  against  the  inclination  of  the  vertical 
images. 

Suppose  we  look  at  a  rectangular  red  cross  (p)  under  the  same  circumstances 
(fig.  263),  on  turning  the  eyes,  i.e.,  the  visual  line,  to  any  vertical  or  hori- 
zontal line  passing  through  p,  the  after-image  is  a  rectangular  cross,  but  it 
appeal's  oblique,  and  its  angles  are  neither  horizontal  nor  vertical  when  the 
eyes  look  obliquely,  i.e.,  when  the  point  of  vision  diverges  considerably  from 
the  above-named  lines.  The  apparently  displaced  crosses  are  shown  in  a,  6, 
c,  d. 

These  oblique  after-images  were  formerly  regarded  as  showing  that  the 
eyeball  rotated  on  its  antero-posterior  axis,  i.e.,  "  wheel  movements.''^  This  is 
not  the  case,  the  movements  are  only  apparent.  If  they  were  real  the  after- 
images ought  to  move  in  the  same  direction  with  both  vertical  and  horizontal 
strips,  but  they  do  not. 

4.  Irradiation. — By  irradiation  is  meant  the  fact  that,  under 
certain  circumstances,  objects  appear  larger  than  they  should  be 
according  to  their  absolute  size  and  distance  from  the  eye,  larger 

^^^^^  than  other  objects  of  greater 

/^  ^^\  ^^^^^^^^       or   less    brightness    of    the 

same  size  and  at  the  same 
distance. 

{a.)  Cut  out  two  circles 
,^^^^^^^^^     as  in  fig.  264,  or  two  squares 
\  /        ^^^^^^^^r        of  exactly  the  same  size,  of 

^-^ -^  ^^^^^^^         white  and  of  black  paper. 

Fig.  264.— Irradiation.  Place  the  white  patch  on  a 

black,  and  the  black  on  a 
white  sheet  of  paper.  Hold  them  some  distance  from  the  eye,  and, 
especially  if  they  be  not  distinctly  focussed,  the  white  circle  will 
appear  larger  than  the  black  one. 


•) 


FlQ.  265. 


FlO.  266. 


{h.)  Divide  a  square  into  four,  as  shown  in  fig.  265,  two  of  the 
smaller  squares  being  white  and  two  black.  Hold  the  figure  at 
some  distance  from  you.     The  two  white  squares  appear  larger,  and 


LXXIII.]  PERIMETRY,   IRRADIATION,   ETC.  347 

they  appear  to  run  into  each  other  and  to  be  joined  together  by  a 
white  bridge. 

(c.)  Look  at  fig.  266,  placed  at  such  a  distance  that  the  accommodation  ia 
imperfect.  The  white  stripe,  which  is  of  equal  breadth  throughout,  appears 
wedge-shaped,  being  wider  below  between  the  broad  black  patches,  and 
narrower  above.  To  me  also  the  narrow  black  patches  appear  to  be  broader 
above  and  narrower  below. 

{d.)  Gum  on  to  a  sheet  of  white  paper  two  strips  of  black  paper  5  mm.  wide, 
and  parallel  to  each  other,  leaving  a  white  interspace  of  8  mm.  between  them. 
Look  at  the  object,  and,  especially  if  it  be  not  sharply  focussed,  the  smaller 
black  strips  will  appear  broader  tlian  the  white  one. 

5.  Imperfect  Visual  Judgments. 

(a.)  ]\Iake  three  round  black  dots,  A,  B,  C,  of  the  same  size,  in 
the  same  line,  and  let  A  and  C  be  equidistant  from  B.  Between 
A  and  B  make  several  more  dots  of  the  same  size.  A  and  B  will 
then  appear  to  be  farther  apart  than  B  and  C. 

(h.)  Make  on  a  white  card  two  squares  of  equal  size,  omitting 
the  outlines.     Across  the  one  draw  horizontal  lines  at  equal  dis- 

SSSSSSSS  88888888 

Fia.  267. 

tances,  and  in  the  other  make  similar  vertical  lines.  Hold  them  at 
some  distance.  The  one  with  horizontal  lines  appears  higher  than 
it  really  is,  while  the  one  with  vertical  lines  appears  broader,  i.e., 
both  appear  oblong. 

(c.)  Look  at  the  row  of  letters  (S)  and  figures  (8).  To  some 
the  upper  halves  of  the  letters  and  figures  may  appear  to  be  the 
same  size  as  the  lower  halves,  to  others  the  lower  halves  may 
appear  larger.  Hold  the  figure  upside 
down,  and  observe  that  there  is  a  con- 
siderable difference  between  the  two, 
the  lower  half  being  considerably  larger 
(fig.  267). 

{(J.)  Zollner's  Lines.— ISfake  two  lines 
parallel  to  each  other.  Note  that  one 
can  judge  very  accurately  as  to  their 
parallelism.  Draw  short  oblique  lines 
through  them.  The  lines  now  no  longer 
appear  to  be  parallel,  but  seem  to  slope 
inwards  or  outwards,  according  to  the  fiq.  zes.-Zoiiner's  Lines, 

direction  of  the  oblique  lines. 

(e.)  Look  at  fig.  268 ;  the  long  lines  do  not  appear  to  be  parallel, 
although  they  are  so. 


348  PRACTICAL  PHYSIOLOGy.  [lXXIII. 

( /'.)  The  length  of  a  hne  appears  to  vary  according  to  the  angle 
and  direction  of  certain  other  lines  in  relation  to  it  (fig.  269).  The 
length  of  the  two  vertical  lines  is  the  same,  yet  one  appears  much 
longer  than  the  other.  (A  large  number  of  similar  illusions  will  be 
found  in  Du  Bois-ReymomVs  Archive  1890, 
\^  y  p.  91,  by  F.  C.  Miiller-Leyer,  and  LAska, 
\/      p.  326.) 

6.  Imperfect  Judgment  of  Distance. 

(a.)  Close   one  eye,    and  hold  the  left 

forefinger  vertically  in  front  of  the  other 

eye,  and  try  to   strike  it  with  the   right 

forefinger.       On   the   first   trial  one   will 

probably  fall  short  of  the  mark,  and  fail 

to  touch  it.     Close  one  eye,  and  rapidly 

try  to  dip  a  pen  into  an  inkstand,  or  put 

a  finger  into  the  mouth  of  a  bottle  placed 

F10.269.-T0  show  False       ^t  a  convenient  distance.     In  both  cases 

Estimate  of  Size.  one  will   not   succeed  at  first.     In  these 

cases  one  loses  the  impressions  produced 

by  the  convergence  of  the  optic  axes,  which  are  important  factors 

in  judging  of  distance. 

(6.)  Hold  a  pencil  vertically  about  15  cm.  from  the  nose,  fix  it 
with  both  eyes,  close  the  left  eye,  and  then  hold  the  right  index- 
finger  vertically,  so  as  to  cover  the  lower  part  of  the  pencil.  With 
a  sudden  move  try  to  strike  the  pencil  with  the  finger.  In  every 
case  one  misses  the  pencil  and  sweeps  to  the  right  of  it. 

(c.)  Fix  a  wire  ring  about  3  inches  in  diameter  into  the  end  of  a  rod  about 
2  feet  in  length.  Hold  the  rod  at  arm's-length,  close  one  eye,  try  to  put 
into  the  ring  a  vertical  process  attached  to  a  rod  of  similar  length  held  in  the 
other  hand. 

7.  Imperfect  Judgment  of  Direction. 

As  the  retina  is  spherical,  a  line  beyond  a  certain  length  when 
looked  at  always  shows  an  appreciable  curvature. 

(a.)  Hold  a  straight  edge  just  below  the  level  of  the  eyes.  *Its 
upper  margin  shows  a  slight  concavity. 

[h.)  In  indirect  vision  the  appreciation  of  direction  is  still  more  imperfect. 
WhUe  leaning  on  a  large  table  fix  a  point  on  the  table,  and  then  try  to  arrange 
three  small  pieces  of  coloured  paper  in  a  straight  line.  Invariably,  the  papers, 
being  at  a  distance  from  the  fixation-point,  and  being  seen  by  indirect  vision, 
are  arranged  not  in  a  straight  line,  but  in  the  arc  of  a  circle  with  a  long 
radius* 

8.  Perception  of  Size. 

Fix  the  centre  of  fig.  270  at  a  distance  of  3  to  4  cm.  from 


LXXIII.] 


PERIMETRY,   IRRADIATION,  ETC. 


349 


the  eye,  when  by  indirect  vision  the  broad  white  and  black  areas 
of  the  peripheral  parts,  bounded  by  hyperbolic  curves,  will  appear 
as  small  aiid  the  lines  bounding  them  as  straight  as  the  smaller 
areas  in  the  middle  zone. 

9.  Convergence  of  the  Visual  Axes  Influences  one's  Concep- 
tions of  Size  and  Distance. 

(a.)  Place  a  blackened  paper  tube  before  each  eye,  look  at  a  fixed 
object,  and  then  gradually  converge  the  tubes ;  the  object  appears 
larger  and  nearer. 


Jia.  ajo. 


(5.)  Look  at  an  object  through  two  pieces  of  glass  (2^x2^x^  in.),  held 

At  first  in  the  same  plane,  one  in  front  of  each  eye.  Let  the  adjoining  edges  of 
the  two  plates  of  glass  be  moved  each  on  a  vertical  axis,  so  that  they  form  either 
a  more  or  less  obtuse  angle  with  each  other.  In  order  to  see  the  object  dis- 
tinctly the  axes  of  the  eyeballs  must  converge  to  a  greater  or  less  extent,  as 
the  case  may  be,  with  the  result  that  the  object  appears  larger  or  smaller,  or 
appears  to  approach  or  recede  as  the  plates  are  rotated.  Special  forms  of 
a]»paratus  contrived  by  Rollett,  and  another  by  Landois,  are  used  for  this 
purpose. 


350 


PRACTICAL  PHYSIOLOGY. 


[LXXIV. 


10.  Apparent  Movements. 

(a. )  Strobic  Discs  — Give  the  discs  a  somewhat  circular  but  rapid  movement 
and  observe  that  the  rings  appear  to  move,  each  one  on  its  own  axis. 

{b.)  Radial  Movement. — 
WhUe  another  person  rotates 
a  disc  like  fig.  271  on  the 
rotating  wheel,  look  steadily 
at  the  centre  of  the  disc. 
One  has  the  impression  as 
if  the  disc  were  covered  with 
circles  which,  arising  in  the 
centre  and  gradually  becom- 
ing larger,  disappear  at  the 
periphery.  After  long  fixa- 
tion look  at  printed  matter 
or  at  a  person's  face ;  the 
letters  appear  to  move 
towards  the  centre,  while 
the  person's  face  appears 
to  become  smaller  and  re- 
cede. If  the  disc  be  rotated 
in  the  opposite  direction, 
the  opposite  results  are  ob- 
tained. 

(c.)  Fix    an  object,   turn 
^^^-  '71-  the  head  rapidly,  and  note 

that  the  object  appears  to 
move  in  an  opposite  direction.  When  the  eye  does  not  move,  we  judge 
that  a  body  is  in  motion  when  the  image  of  that  body  falls  successively  on 
ditferent  points  of  the  retina,  and  at  the  same  time  are  conscious  that  the 
ocular  muscles  have  not  contracted  {Beaunis). 


LESSON  LXXIY. 


KUHNE'S    ARTIFICIAL     EYE  —  MIXING    COLOUR 
SENSATIONS— COLOUR-BLINDNESS. 


1.  Kuhne's  Artificial  Eye  (fig.  272). 

(a.)  Fill  the  instrument  with  water,  and  place  it  in  a  darkened  room  with 
the  cornea  directed  to  a  hole  in  a  shutter,  through  which  sunlight  is  directed 
by  means  of  a  heliostat.  If  this  is  not  available,  use  an  oxy-hydrogen  lamp 
or  electric  light  to  throw  parallel  rays  of  light  on  the  cornea.  If  these  cannot 
be  had,  use  a  fan-tailed  gas-lnirner,  but  in  this  case  the  illumination  and 
images  will  be  feeble.  To  enaMe  one  to  observe  the  course  of  the  rays  of  light, 
pour  some  eosin  or  fluorescin  into  the  water  in  the  instrument. 

(6.)  Formation  of  an  image  on  the  retina.  Observe  the  course  of  the  rays 
of  light,  which  come  to  a  focus  behind  the  lens — the  principal  posterior  focus. 
Move  the  ground  glass  representing  the  retina,  and  get  a  clear  inverted  image 
of  the  source  of  light.  N.B. — In  this  instrument  accommodation  is  effected 
not  by  altering  the  curvature  of  the  lens,  as  in  the  normal  eye,  but  by  nwving 
the  retina. 


LXXIV.] 


kDhne's  artificial  eye. 


351 


(c.)  Place  convex  and  concave  lenses  between  the  source  of  liglit  and  the 
cornea  ;  observe  how  each  alters  the  course  of  the  rays  and  their  focus. 

{d.)  After  having  an  image  well  focussed  upon  the  retina,  move  the  latter 
away  from  the  lens,  when  the  image  becomes  blurred  owing  to  diffusion.  If, 
however,  a  slip  of  zinc,  with  a  hole  cut  in  it  to  act  as  a  diaphragm  to  cut  oif 
some  of  the  marginal  rays,  be  interposed,  the  image  is  somewhat  improved. 

{e.)  After  seeing  that  the  light  is  sharply  focussed  on  the  retina,  remove  the 
lens— to  imitate  the  condition  after  removal  of  the  lens  for  cataract— and 
observe  that  the  rays  are  focussed  quite  behind  the  retina. 

(/.)  Place  the  removed  lens  in  front  of  the  cornea,  the  principal  focus  is 
now  much  in  front  of  the  retina,  so  that  a  much  weaker  lens  than  the  one 
removed  hns  to  be  used  after  removal  of  the  lens  for  cataract. 


Fig.  27a.— Kuhne's  Artificial  Eye,  as  made  by  Jung  of  Heidelberg 


{g.)  Astigmatism.— Fill  the  plano-convex  glass  (^r)— to  imitate  a  cylindrical 
lens— with  water,  and  place  it  in  front  of  the  cornea.  Between  the  cornea 
and  the  cylindrical  lens  place  a  sheet  of  zinc  with  a  cross  cut  out  in  it,  or  with 
a  number  of  holes  in  a  horizontal  line.  One  cannot  obtain  a  distinct  image  of 
the  cross  or  the  holes,  as  the  case  may  be. 

(Ji.)  Scheiner's  Experiment.— With  the  light  properly  adjusted,  place  in 
front  of  the  cornea  a  i)iece  of  zinc  perforated  with  two  holes  {c),  i  cm.  in 
diameter,  in  a  horizontal  line,  the  distance  between  the  holes  being  less  than 
the  diameter  of  the  pupil.  Find  the  position  of  the  retina— and  there  is  only 
one  position— in  which  the  two  beams  of  light  are  brought  to  a  focus.  Move 
the  retina  towards  the  cornea,  and  observe  two  images  ;  close  the  right-hand 


352 


PRACTICAL  PHYSIOLOGY. 


[lxxiv. 


hole  and  the  right-hand  image  disappears.  Bring  the  retina  posterior  to  the 
principal  focus,  and  again  there  are  two  images.  On  closing  the  right-hand 
hole  the  left  hand  image  disappears,  and  vice  versd. 

2.  Hering's  Apparatus  for  Mixing  the  Colours  of  Coloured  Glasses. 

By  mixing  two  primary  colours  (red,  yellow,  green,  blue),  one  may  obtain 
all  intermediate  hues,  and  by  mixing  three  colours  (red,  green,  and  blue,  or 
yellow,  green,  and  violet),  one  can  obtain  white.  The  apparatus  consists  of  a 
box  k  (fig.  273),  two  pieces  of  mirror  glass  {s  and  s{),  each  placed  at  an  angle  of 
45"  to  the  horizontal  plane  as  shown  in  fig.  274.  The  base  of  the  box  consists 
of  a  coloured  glass  (/o),  while  the  lower  half  of  the  right  lateral  wall  is 
filled  with  the  coloured  glass  plate  {f^\  and  the  upper  half  of  the  left  wall  by 
the  coloured  glass  ]tlate  (/).  The  white  gLss  plates  (W,  W,,  "Wo)  reflect  light 
through  the  coloured  glasses  (fig.  273).     The  light  transmitted  from  below, 


Fio.  273. — Bering's  Appaiatus  for  Mixing 
Coloured  Light  k.  Box;  t,  <].  Lids: 
W,  Wx,  W2.  WTiite  reflecting  surfaces. 


Fig.  274.— Scheme  of  Fig.  273-  /,/i,/2-  Col- 
oured  glasses.  W,  W'l.ITa.  White  reflect- 
ing surfaces ;  «,  sj.  Glass  plates. 


and  that  from  the  two  sides,  is  transmitted  by  a  tube  to  the  observer's  eye. 
The  brightness  can  b3  varied  by  adjusting  the  white  reflecting  surfaces,  which 
are  placed  opposite  a  well-lighted  window.  By  means  of  three  small  metallic 
doors  {t,  t^ )  any  one  of  the  colours  can  be  cut  oS".  Thus  any  combination  of 
coloured  lights  can  be  made,  as  the  glasses  are  movable.  The  writer  has 
found  it  best  to  put  the  violet  or  blue  lowermost. 

3.  Mixing  Colour  Sensations. 

{a.)  Lambert's  Method. — On  a  black  background  place  a  blue 
wafer  or  square  of  blue  paper,  and  6  or  7  inches  behind  it  a 
yellow  square  or  wafer.  Hold  a  plate  of  clear  glass  vertically, 
about  10  inches  above  and  midway  between  the  two  squares. 
Look  obliquely  through  the  glass,  and  get  the  reflected  image  of 


LXXIV.] 


COLOUR-BLINDNESS. 


353 


yellow  to  overlap  the  blue,  seen  directly  through  the  glass ;  where 
they  overlap  appears  ichiie.  Hering  has  arranged  a  large  form  of 
this  apparatus  suitable  for  class  purposes. 

{h.)  Arrange  on  the  sjtindle  of  the  rotating  apparatus  the  disc  with  coloured 
sectors  provided  for  you  (fig.  275).  On  rotating  the  disc  rapidly,  observe  that 
it  appears  grey  or  whitish.  The  disc  is  provided  with  sectors  corresponding 
to  the  colours  of  the  S])ectrum,  and  arranged  in  varying  proportions. 

(c.)  Arrange  three  of  Clerk-Maxwell's  colour  discs — red,  green,  and  violet 
— upon  the  spindle  of  the  rotating  apparatus.  Adjust  the  relative  amounts 
of  these  three  colours,  so  that  on  rapidly  rotating  them  they  give  rise  to  the 
sensation  of  grey  or  white.  Each  disc  is  of  a  special  colour,  and  has  a  radial 
slit  from  the  centre  to  the  circumference.  This  slit  enables  a  disc  of  a  different 
colour  to  be  slij-ped  over  the  other,  and  thus  many  discs  can  be  superposed, 
and  the  amount  of  each  colour  exposed  regulated  in  any  desired  proportion. 


Fia.  275.— Rothe's  Rotatory  Apparatus  for  Colour  Discs.    It  Is  so  arranged  as  to  give 
various  rates  of  rotation  by  combining  the  motions  of  i,  2,  and  3. 


{d.)  Combine  a  chrome-yellow  disc  and  a  blue  one  in  various  proportions, 
and  on  rotating,  the  resultant  colour  is  never  green,  but  a  yellowish-  or  reddish- 
grey. 

(e.)  Arrange  two  coloured  discs  of  vermilion  and  bluish-green  in  the  pro- 
I)ortion  of  36  of  the  former  to  64  of  the  latter.  On  the  same  spindle  arrange 
a  white  and  a  black  disc — with  a  diameter  a  little  more  than  half  that  of  the 
former  pair— the  white  being  in  the  proportion  of  21.3  to  78.7  of  the  black. 
On  rotating,  a  grey  colour  is  obtained  from  both  sets  of  discs. 

4.  To  Test  Colour-Blindness. — On  no  account  is  the  person 
being  tested  to  be  asked  to  name  a  colour.  In  a  large  class  of 
students  one  is  pretty  sure  to  find  some  who  are  more  or  less  colour- 
blind.    The  common  defects  are  for  red  and  green. 


354       .  PRACTICAL  PHYSIOLOGY.  [LXXIV. 

(a.)  Place  Holmgren's  worsteds  on  a  white  background  in  a 
good  light.  Select,  as  a  test  colour,  a  skein  of  a  light  green  colour, 
such  as  would  be  obtained  by  mixing  a  pure  green  with  white. 
Ask  the  examinee  to  select  and  pick  out  from  the  heap  all  those 
skeins  which  appear  to  him  to  be  of  the  same  colour,  whether  of 
lighter  or  darker  shades.  A  colour-blind  person  will  select 
amongst  others  some  of  the  confusion-colours,  e.g.,  pink,  yellow. 
A  coloured  plate  showing  these  should  be  hung  up  in  the  labora- 
tory. Any  one  who  selects  all  the  greens  and  no  confusion-colours 
has  normal  colour  vision.  If,  however,  one  or  more  confusion- 
colours  be  selected,  proceed  as  follows: — Select,  as  a  test  colour,  a 
skein  of  pale  rose.  If  the  person  be  red-blind,  he  will  chose  blue 
and  violet ;  if  green-blind,  grey  and  green. 

(h.)  Select  a  bright  red  skein.  The  red-blind  will  select  green 
and  brown  :  the  green-blind  picks  out  reds  or  lighter  brown. 

5.  Contrast  and  Simultaneous  Contrast. 

The  following  are  examples  of  simultaneous  contrast  where 
stimulation  of  the  retino-cerebral  apparatus  modifies  the  sensations 
excited  by  a  different  portion  of  the  retina  when  the  compared 
objects — light  or  colour — are  looked  at  simultaneously.  Contrast 
phenomena  were  carefully  studied  by  Chevreul  in  relation  to  the 
effects  produced  by  colours  juxtaposed  in  tapestry  in  the  Gobelin's 
factory  of  Paris.  Contrast  may  apply  to  size,  light,  colour,  and  it 
may  be  simultaneous  or  successive. 

(a.)  Place  a  small  white  square  or  oblong  piece  of  paper  or  cross 
on  a  dull,  black  surface.  Stare  steadily  at  the  white  square,  and 
observe  that  the  edges  appear  whiter  than  the  centre ;  indeed,  the 
centre  by  contrast  may  appear  greyish.  A  white  strip  of  paper 
placed  between  two  black  strips,  looks  white  at  the  margin  near 
the  black. 

(A.)  Look  with  one  eye  at  the  sky  through  a  i-inch  blackened 
tube,  both  eyes  being  open.  The  field  of  vision  looks  much  brighter 
when  seen  through  the  tube  than  is  the  case  with  the  other  eye. 

(r.)  Place  side  by  side  a  white  and  black  surface.  Cut  two 
oblong  (ii-"xi")  pieces  of  grey,  yellow,  or  other  coloured  paper 
of  exactly  the  same  size,  and  lay  one  piece  of  the  grey  on  the  white 
background,  and  the  other  on  the  black.  Observe  how  much 
brighter  the  latter  looks  owing  to  contrast.  Reverse  the  pieces, 
and  notice  that  the  same  result  occurs.  Repeat  with  other 
colours. 

(d.)  On  the  rotating  machine  cause  a  disc,  as  in  fig.  276,  to 
rotate  with  moderate  rapidity,  when  several  zones  will  be  seen,  the 
innermost  black,  while  each  one  farther  outwards  is  lighter  in  tint. 
Each  zone,  where  it  abuts  against  the  inner  darker  zone,  is  Kghtei 


LXXIV.]  CONTRAST.  355 

than  the  rest  of  the  same  zone,  and  shades  off  gradually  to  the 
outer  part  of  the  zone. 

(e.)  Take  two  pieces  of  different  coloured  paper  (say  pale  red  and 
pale  green)  and  place  them  side  by  side.  Fix  two  similar  strips 
apart  from  each  other  and 
distant  from  the  other  two. 
The  two  slips  juxtaposed 
differ  in  colour  from  the 
isolated  pieces.  In  the  juxta- 
posed slips  the  colour  of 
the  one  influences  the  colour 
of  the  other,  i.e.,  each  one 
looks  as  if  it  were  mixed 
with  a  certain  amount  of 
the  complementary  colour 
of  the  juxtaposed  slip 
(GJ  ewe  III). 

(/.)  Place  on  a  table  a  small 
sheet  (4"  X  4")  of  red  and  one  of 
green  paper.     Cut  out  of  a  sheet  I^'iO-  276.— Disc  for  Contrast, 

of  red    paper   two   pieces   about 

1  inch  square,  and  place  them  on  tlie  two  large  squares.  Observe  that  the 
small  red  square  on  the  green  ground  appears  far  brighter  and  more  saturated 
than  the  red  square  on  the  red  ground. 

((/.)  Cut  a  small  hole  (5x5  mm.)  in  a  piece  of  coloured  paper,  e.g.,  red, 
and  look  through  the  hole  at  a  sheet  of  white  paper,  the  hole  appears 
greenish. 

(//.)  On  a  mirror  ])lace  a  slip  of  transparent  coloured  glass,  e.g.,  red  or  green. 
Hold  in  front  of  the  coloured  glass  a  narrow  stri|)  of  white  paper  ;  by  adjust- 
ing the  position  of  the  glass  in  relation  to  the  light,  we  see  two  images  reflected 
from  the  anterior  and  posterior  surface  of  the  mirror  ;  one  has  the  same  colour 
as  the  coloured  glass,  while  the  other  or  posterior  one  has  the  complementary 
colour  ;  if  a  red  glass  be  used  the  latter  is  green,  if  a  green  glass  it  is  red. 
Hold  in  front  of  the  red  glass  a  piece  of  white  paper  with  black  printed  matter 
on  it.  The  black  })rint  is  seen  green  in  the  posterior  image.  Gum  a  few 
narrow  strips  of  white  })aj)er  (i  mm.  in  diameter)  on  black  paper,  and  on  hold- 
ing it  up  in  front  of  the  red  glass,  as  before,  the  anterior  image  a})pears  in  the 
complementary  colour  of  the  glass,  viz.,  green. 

(/. )  Place  four  lighted  candles  in  a  dark  room  before  a  white  surface,  and 
push  between  the  candles  and  the  screen  towards  the  centre  of  the  series  an 
opaque  screen,  e.g.,  cardboard,  with  a  clean-cut  vertical  edge.  A  part  of  the 
white  surface  is  illuminated  by  all  four  candles,  then  a  vertical  area  illumi- 
nated by  three,  and  so  on,  and  finally  a  part  not  illuminated  by  any  of  the 
candles.  Each  of  these  areas  is  throughout  its  entire  extent  equally  illumi- 
nated, yet  on  the  side  where  each  area  abuts  against  a  darker  area  it  ajjpears 
lighter,  on  the  other  side  darker,  and  gradually  shaded  between  its  outer  and 
inner  limits.  This  is  due  to  the  fact  that  strong  stimulation  of  one  part  of 
the  retina  diminishes  the  excitability  in  the  other  parts,  and  the  parts  most 
affected  are  those  next  the  excited  area.  Thus  a  change  in  the  excitability 
of  one  part  of  the  retina  is  brought  about  by  stimulation  of  an  adjacent 
part. 


356 


PRACTICAL    PHYSIOLOGY. 


[LXXIV. 


(/.)  H.  Meyer's  Experiments  on  simultaneous  contrast, 
(i.)  Cut  out  a  small  oblong  of  white,  or  preferably  of  grey,  paper, 
and  put  it  on  a  large  piece  of  bright  green  paper  (4  inches  square) ; 
the  grey  sufters  no  change.     Cover  the  .whole  with  a  thin  semi- 
transparent  sheet  of  tissue  paper.     The  grey  oblong  appears  pinli. 

(ii.)  Instead  of  green  paper  place  the  grey  slip  on  red,  and  cover 
it  as  l3efore  ;  a  greenish-blue  contrast  colour  is  seen. 

(iii.)  Repeat  (a.),  but  place  a  red  square  on  a  grey  ground ;  the 
red  square  will  appear  greenish. 

(iv.)  A  grey  square  upon  blue  appears  yellow ;  a  yellow  upon 

blue  appears  white,  when 
covered  with  tissue  paper. 
All  the  above  are  modifica- 
tions of  H.  Meyer's  experi- 
ment. The  tissue  paper  is 
used,  as  contrast  colours  are 
far  more  readily  excited 
by  pale  than  by  saturated 
colours,  so  that  differences 
of  sensation  are  much  greater 
with  weak  than  with  strong 
stimulation. 

(v.)  Surround  the  small 
square  with  a  broad  black 
line,  each  square  appears  in 
its  own  colour.     The  effect 

Fig.  277--Disc  for  Simultaneous  Contrast  ^f  contrast  is  destroyed. 


(Jc)  Place  side  by  side  two  strips  of  paper,  green  and  red  (6x3  in.).  Over 
the  Hne  of  junction  place  a  strip  of  grey  paper  (i  x  6  in.),  and  cover  the  whole 
with  tissue  paper,  as  before.  The  grey  appears  pink  on  the  green  side,  and 
greenish  on  the  red.  This  contrast  is  also  set  aside  by  running  a  black 
margin  round  the  grey  strip.     Do  the  same  with  yellow  and  blue. 

(Z.)  Arrange  a  disc  like  tig.  277  on  the  rotating  wheel. 
On  a  white  disc  fix  four  narrow,  coloured  {e.g.,  green) 
sectors,  and  interrupt  each  in  the  middle,  as  in  the 
figure,  with  a  black  and  white  stripe.  On  rotating  the 
disc,  the  ring,  which  one  might  expect  to  be  grey  from 
the  black  and  white,  appeai-s  reddish,  i.e.,  the  comple- 
mentary colour  of  the  greenish  ground. 

{m.)  Place  a  strip  of  grey  paper  on  a  black  background 
and   a   corresponding  strip   on    a   white   ground.     The 
fonner  will   appear  much   lighter,  the  grey  on   white 
much  darker.    Fix  the  eyes  for  a  minute  on  a  point  mid- 
way between  the  strips  ;  close  and  cover  the  eyes.     The 
after-images  will  show  a  great  difference  in  luminosity, 
(n.)  Ragona  Scina's  Experiment. — Two  pieces  of  wood  fixed  at  right  angles 
to  each  other  are  covered  by  white  paper,  while  a  coloured  sheet  of  glass  is 
held  at  an  angle  of  45°  between  them  (fig.  27S),  or  the  apparatus  of  Hering  (fig. 


Fig.  273.  —  Kagona 
Sciua's  Experi- 
ment. 


LXXIV.] 


CONTRAST. 


35r 


2/9;  may  be  used.  Look  vertically  through  the  glass  at  the  horizontal  whiti 
paper,  and  observe  a  pale  red  tint.  Attach  a  small  black  square  to  the  centre  of 
the  vertical  arm  at  B,  the  image  of  tliis  square  is  seen  at  6  as  a  deep  red  image. 
Place  a  similar  black  square  on  the  horizontal  board  at  C,  it  should  appea* 
grey  ;  but  a  grey  on  a  red  ground  causes 
contrast,  and  so  one  sees  a  greenish-blue 
square  alongside  a  red  one. 

6.  Hering's  Apparatus  for  Simultaneotis 
Contrast. 

{a  )  By  means  of  one  or  two  doubly 
refractive  prisms  (fig.  280,  P,  P)  a  double 
image  is  obtained  of  narrow  strips  of 
coloured  paper  placed  either  on  a  white  or 
a  coloured  background.  If  blue  be  placed 
on  yellow,  the  double  image  is  bluish,  and 
if  yellow  be  placed  on  blue,  the  double 
image  is  yellowish  {PJiiiger^s  Archiv,  vol. 

47,  P-  237)- 

(b.)  The  apparatus  of  Hering  (fig.  281) 
is  also  useful  for  simultaneous  contrast. 
Coloured  glasses  {e.g.,  blue  and  red)  are 
placed  in  P  and  P',  and  light  is  reflected 
through  them  by  the  adjustable  white 
surfaces  (W,  W).  On  looking  at  a  narrow 
black  strip  (S)  on  a  white  ground,  one  sees 
contrast  phenomena  according  to  the  colours  of  the  glass  used. 

The  white  surface  in  front  of  the  red  glass,  when  looked  at  with  one  eye,  is 
red,  just  as  that  in  front  of  the  blue  glass  is  blue  under  the  same  conditions. 
Focus  the  eyes  for  an  object  nearer  than  the  black  strip  on  the  white  ground. 


Fig.  279.— Hering's  ApparatuB  fop 
Contrast. 


FlQ.  280.— Hering's  Apparatus  for  Simultaneous 
Contrast  with  Binocular  Vision  by  two 
Doub'.y  Refractive  Prisms,  P,  P.  0.  Glass 
to  avoid  reflection. 


Fig.  281.— Hering's  Apparatus  for  Simultaneous  Con- 
trast. P,  P".  Coloured  glasses:  TF,  W.  Whita 
reflectors ;  S.  Black  line  on  white  surface. 


This  is  done  by  looking  at  a  bead  {k)  fixed  on  the  point  of  a  rod  (supplied 
with  the  instrument),  the  latter  being  held  between  the  eyes  fad  ^b"  "'I'ita 
ground.  The  black  strip  seen  under  these  conditions  forms  a  double  imog,., 
i.e.    its  image  is  formed  on  two  non-corresponding  parts  of  the  retina.     The 


358  PRACTICAL  PHYSIOLOGY.  [LXXIV. 

two  images  are  in  stroncc  contrast,  while  the  two  surrounding  areas  scarcely 
contrast  at  all.     (Hering's  apparatus  is  made  by  Rothe,  Wenzelbad,  Prague.) 

There  are  two  theories  of  contrast,  viz.,  that  of  Helmholtz,  the 
"psychological  theory,"  and  the  " phj'siological  theory,"  of  which 
Hering  is  the  chief  supporter.  Hering  has  devised  many  experiments 
in  support  of  his  contention.  The  former  theory  represents  contrast 
as  due  to  an  error  of  judgment.  On  the  physiological  theory,  Hering 
supposes  that  there  are  material  chemical  changes  in  a  hypothetical 
retino-cerebral  "vision-stuff"  ("  Seh-stoff ").  These  changes  may 
he  assimilative  (anaboHc)  (black,  blue,  green),  or  dissimilative 
(kataboUc)  (white,  yellow,  red).  A  change  in  one  area  may 
influence  the  retino-cerebral  apparatus  outside  the  area  directly 
affected  by  the  stimulus. 

7.  Hering's  Experiment  on  Simultaneous  Contrast. 

Divide  a  large  quadrilateral  sheet  of  paper  vertically  into  halves, 
And  make  one  half  black  and  the  other  white.  Near  the  centre  of 
the  vertical  division  gum  two  V-shaped  pieces  of  grey  paper  (one 
on  the  black  and  the  other  on  the  white  half)  with  their  apices 
together.  Tlie  V  on  the  black  looks  lighter  by  contrast  than  that 
on  the  white.  Fix  the  V's  for  a  minute,  and  then  look  at  a  uniform 
surface.  Even  after  the  after-image  of  the  back  grounds  has 
disappeared,  the  after-image  of  the  V  on  the  black  ground  looks 
darker  than  that  of  the  V  on  the  light  ground.  This,  Hering  con- 
tends, must  be  due  to  a  material  change  taking  place  in  a  localised 
part  of  the  retino-cerebral  apparatus.  It  seems  difficult  to  explain 
this  result  as  dependent  upon  an  error  of  judgment  due  to  the 
influence  of  the  background.  Hering  regards  this  as  a  fundamental 
experiment  in  support  of  his  theory.  Similar  experiments  may  be 
made  with  coloured  papers. 

8.  Successive  Light  Induction  {Hering). 

(a. )  Look  for  one  minute  at  a  small  white  circular  disc  on  a  black  back- 
ground, e.g.y  velvet.  Close  and  cover  the  eyes.  A  negative  afler-image  of 
the  disc  appears,  but  it  is  darker  and  blacker  than  the  Wsual  area,  and  it  has 
a  peculiar  light  area  round  it,  brightest  close  to  the  disc,  and  fading  away 
from  it. 

(6.)  Look  at  two  small  white  square  patches  of  paper  placed  one-eighth  of 
an  inch  apart  on  a  black  l»ackground.  On  closing  the  eyes,  the  black  space 
between  them  looks  brighter  than  the  other  three  sides  of  the  squares. 

(c.)  Look  at  a  black  strip  on  a  white  ground.  On  closing  the  eyes  there  is 
no  partial  darkening  of  the  white  ground,  but  only  an  intensely  bright  image 
of  the  strip, 

9.  Coloured  Shadows. 

[n.)  Place  an  opaque  vertical  rod  I'l  inch  in  diam. )  in  front  of  a  white  back- 
ground. Admit  not  too  bright  daylight  to  cast  a  shadow  of  the  rod.  Place 
a  lighted  candle  behind  one  side  of  the  rod,  the  shadow  caused  by  the  yellow- 


LXXIV.]  CONTRAST.  359 

red  light  of  a  caudle,  and  illuminated  by  the  daylight,  appears  blue,  i.e.,  a 
purely  subjective  blue,  the  complementary  colour  of  the  yellow-red  light  of 
the  candle,  which  casts  a  yellow  light.  The  effect  is  more  pronounced  the 
darker  both  shadows  are.  To  show  that  the  blue  is  purely  subjective,  roll  up 
a  sheet  of  black  paper— black  surface  innermost — in  the  form  of  a  tube  about 
\  inch  or  less  in  diameter.  At  a  distance  of  i8  inches  look  at  the  centre  of 
the  blue  shadow,  and  let  an  observer  cut  off  the  light  from  thi^  candle  by 
means  of  an  opaque  screen.  On  removing  the  screen  no  change  is  visible, 
but  if  the  tube  be  directed  to  the  line  of  junction  of  the  blue  shadow,  with 
the  illuminated  background  just  beyond  it,  the  blue  appears. 

{h.)  In  a  window-shutter  of  a  dark  room  cut  two  square  holes  (lo  cm.)  on 
the  same  horizontal  plane,  and  2  feet  apart.  In  one  fix  a  piece  of  clear  glass 
to  admit  ordinary  white  light,  and  into  the  other  fit  a  red  or  green  coloured 
glass.  Both  openings  must  be  provided  with  a  movable  shutter  to  regulate 
the  amount  of  light  admitted.  At  3-4  feet  distance  place  a  rod  or  flat  piece 
of  wood  vertically  against  a  white  surface.  Observe  two  shadows.  Suppose 
the  glass  to  be  red,  then  the  shadow  due  to  the  ordinary  light  is  red,  that  of 
the  red  glass  is  greenish.  Substitute  for  the  red  light  that  of  a  lighted  candle. 
The  shadow  then  appears  blue. 

10.  Choroidal  Illumination. 

(a.)  In  a  dark  room  light  an  ordinary  lamp  or  fan-tailed  gas-burner.  Place 
the  source  of  light  at  the  right  side,  about  2  feet  from  an  open  book  or  sheet 
of  paper.  Partly  separate  the  fingers  of  the  left  hand  and  place  them  over  the 
face,  so  that  different  portions  of  the  paper  are  seen  by  each  eye.  That  half  of 
the  page  seen  with  the  right  eye  has  a  greenish  tint,  the  other  part  seen 
with  the  left  eye  is  red  or  pinkish.  Change  the  source  of  light  to  the  left  side, 
the  colours  are  reversed. 

{b.)  With  the  conditions  as  in  (a.),  hold  a  piece  of  paper  (3-4  cm.  wide),  ora 
visiting-card,  between  the  eyes  with  its  flat  surface  towards  the  face,  the  same 
phenomena  are  seen. 

(c.)  Cut  in  a  piece  of  black  cardboard  two  rectangular  holes  (4  x  10  mm.), 
separated  by  a  di.stance  about  equal  to  that  between  the  pupils,  with  the  con- 
ditions as  in  {a.).  Hold  the  cardboard  about  10  inches  or  more  from  you, 
and  look  through  the  holes  at  a  white  surface  ;  four  images  of  the  two  holes 
will  be  seen  ;  the  inner  right  and  outer  left  images  are  impressions  f^rom  the 
right  eye,  the  inner  left  and  outer  right  from  the  left  eye.  This  is  easily 
proved  by  closing  either  eye,  when  the  images  belonging  to  that  eye  disappear. 
If  the  source  of  light  be  on  the  right  side,  the  former  pair  of  images  is  greenish 
in  colour,  the  latter  is  pale  pink.  Change  the  light  to  the  left  side  and  the 
colours  are  reversed  (//.  Sewall).  Tlie  colour- phenomena  occur  witliout  the  aid 
of  objective  colour,  and  are  due  to  light  passing  through  the  sclerotic  and 
choroid  coats. 

11.  Binocular  Contrast. 

Place  a  white  strip  of  paper  on  a  black  surface,  look  at  the  white  paper 
and  squint  so  as  to  get  a  double  image.  In  front  of  the  right  eye  hold  a  blue 
glass,  and  in  front  of  the  left  one  a  grey  (smoked)  glass.  The  image  of  the 
right  eye  will  be  blue,  that  of  the  left  yellow.  Instead  of  the  grey  glass,  a 
card  with  a  small  hole  in  it  placed  in  front  of  the  left  eye  does  perfectly  well. 
The  yellow  of  the  left  eye  is  a  contrast  sensation. 

12.  Positive  After-images. 

(a.)  In  a  room,  not  too  brightly  illuminated,  rest  the  retina  by 
closing  the  eyes  for  a  minute.     Suddenly  look  for  two  seconds  at  a 


360  PRACTICAL  PHYSIOLOGY.  [LXXIV. 

gas-jet  surrounded  with  a  white  globe,  then  close  the  eyes.     An 
image  corresponding  to  that  looked  at  will  be  seen. 

{b.)  Rest  the  retina  by  closing  the  eyes,  then  look  at  a  gas- 
flame  surrounded  with  a  coloured  glass,  or  look  at  a  gas-flame  in 
wliich  some  substance  is  burned  to  give  a  characteristic  flame,  e.g., 
common  salt.  Then  look  at  a  white  surface,  when  a  positive  after- 
image of  the  same  colour  will  be  seen.  In  all  these  cases  the 
image  moves  as  the  eye  is  moved,  showing  that  we  have  to  do  with 
a  condition  within  the  eye. 

13.  Negative  After-images.  These  are  regarded  as  a  sign  of 
retino-cerebral  fatigue.— Successive  Contrast. 

(a.)  Rest  the  retina,  and  then  stare  steadily  for  half  a  minute  or 
less  at  a  small  white  square  or  white  cross  on  a  black  ground.  To 
ensure  fixation  of  the  eyeballs,  make  a  small  mark  in  the  centre  of 
the  white  paper,  and  fix  this  steadily.  Then  suddenly  slip  a  sheet 
of  white  paper  over  the  whole,  a  black  square  or  cross  will  appear 
on  the  white  background.  I  find  that  the  best  black  surface  to  use 
is  the  dull  black  of  the  "  Tuch-papier,"  such  as  is  used  by  opticians 
for  Uning  optical  apparatus.  Notice  also  while  staring  at  the  white 
paper  that  its  margins  appear  much  brighter  than  the  centre,  owing 
to  contrast. 

{b.)  The  black  negative  after-image  may  also  be  seen  by  closing 
the  eyes. 

(c.)  Look  at  a  black  square  or  cross  on  a  white  ground.  Turn 
to  a  grey  surface,  when  a  white  square  or  cross  will  appear. 

{(i.)  Stare  intensely  at  a  bright  red  square  on  a  black  surface 
for  twenty  seconds,  and  then  look  at  a  white  surface :  a  bluish- 
green  patch  on  the  white  is  seen.  It  waxes  and  wanes,  and  finally 
vanishes. 

(e.)  A  green  stared  at  in  the  same  way  gives  a  red,  i.e.j  in  each 
case  the  complementary  colour  is  obtained  as  a  "  negative  coloured 
after-image." 

(/.)  Place  a  small  red  and  a  small  green  square  side  by  side  on 
a  black  background,  stare  at  them,  and  quickly  cover  the  whole 
w^ith  a  sheet  of  white  paper  :  a  greenish-blue  after-image  wiU  appear 
in  place  of  the  red,  and  a  reddish-purple  instead  of  the  green. 

These  negative  after-images  are  examples  of  so-called  "  Succes- 
sive Contrast." 

14.  Haploscope  (dTrXoo? — single). 

Place  the  eyeballs  in  the  primary  position,  i.e.,  look  straight 
ahead  at  a  hypothetical  object  on  a  level  with  the  eyes,  but  placed 
at  the  horizon.  The  visual  axes  are  parallel,  and  we  have  two 
distinct  and  separate  fields  of  vision.     On  looking  through  two 


LXXIV.] 


STEREOSCOPE. 


361 


V 


Fig.  282.— To  illustrate  Haploscopic  Vision, 


parallel  tubes  placed  one  in  front  of  each  eye,  one  obtains  two 
different  retinal  pictures.  Nevertheless,  single  vision  is  the  result, 
and  the  two  different  pictures  are  combined  to  give  an  illusory 
sensation  of  one  object.  One  gets  approximately  haploscopic  vision 
with  a  stereoscope. 

Haploscopic  vision  may  be  illustrated  by  vertical  lines,  parts  of 
circles  (Hering,  Hermann'' s  Handhuch  d.  Physiologie^  iii.  p.  355), 
or  by  the  familiar  bird 
and  cage  experiment  (fig. 
282).  Hold  the  figure 
close  to  the  eyes,  separate 
the  two  fields  of  vision 
by  a  card  held  vertically 
in  the  mesial  plane  be- 
tween the  eyes,  and  look 
beyond  the  picture,  i.e., 
allow  the  eyeballs  gradu- 
ally to  diverge  from  the  point  of  convergence.  On  doing  so,  as 
the  visual  axes  become  less  convergent,  one  has  on  the  right  visual 
field  a  bird,  on  the  left  a  cage, — the  bird  appears  to  move  into  the 
cage,  and  in  consciousness  we  have  the  illusion  as  if  the  bird  were 
in  the  cage. 

15.  Stereoscope. 

{a.)  Examine  a  series  of  stereoscopic  slides  to  show  the  combina- 
tion of  the  images  obtained  by  the  right  and  left  eyes  respectively. 

{Ik)  Struggle  of  the  Fields  of  Vision. — Place  in  a  stereoscope 
a  slide  of  glass  with  vertical  lines  ruled  on  one  half  of  it  and  hori- 
zontal lines  on  the  other  half.  Look  at  the  two  dissimilar  images ; 
note  that  they  are  not  combined,  but  sometimes  one  sees  it  may  be 
only  the  horizontal,  at  another  only  the  vertical  lines.  It  may  be 
done  also  with  coloured  slides. 

(c.)  Lustre. — Use  a  stereoscopic  sUde,  preferably  a  geometrical 
pattern,  e.g.,  a  crystal  where  the  boundary-Hnes  are  white  and  the 
surfaces  black.     Such  a  slide  shows  glance  or  lustre. 

]  6.  Lustre  in  Coloured  Objects. 

This  may  be  shown  by  looking  at  a  green  patch  (electric  green)  on  a  red 
ground  through  coloured  glass,  e.g.,  a  blue  glass  before  one  eye  and  a  red  one 
before  the  other  eye.     Other  combinations  may  be  made, 

17.  StereoBcopy  Dependent  on  Differences  of  Colour. 

{a.)  Difference  of  colour  may  be  the  cause  of  an  apparent  difference  in 
distance.  If  one  looks  from  a  distance  of  3  metres  at  red  and  blue  letters 
(8x4  cm.)  on  a  black  background,  to  most  observers  the  red  appears  nearer 
than  the  blue.  It  is  usual  to  explain  this  by  difference  of  accommodation, 
more  effort  being  required  to  focus  for  the  red  letters  than  for  the  blue  ;  and 


362  PRACTICAL   PHYSIOLOGY.  [LXXIV. 

hence  the  red  is  regarded  as  nearer.  This  is  not  a  sufficient  explanation,  as 
many  see  the  blue  nearer  than  the  red.  The  apparent  difference  disappears 
on  closure  of  one  eye,  but  on  opening  the  other  eye,  the  difference  of  distance 
asserts  itself.  Is  this  due  to  stereoscopy?  Einthoven  supposes  that  it  is. 
(Einthoven,  '•  On  the  Production  of  Shadow  and  Perspective  Effects  by  Difference 
of  Colour,"  ^ram,  1893,  p.  191.) 

{b.)  Briicke  showed  that  the  retinal  images  of  differently  coloured  points 
are  shifted  with  respect  to  one  another.  Fix  on  a  black  background  a  narrow 
vertical  strip  of  })aper,  the  upper  and  lower  thirds  being  red  and  the  middle 
third  blue.  On  looking  at  the  strip  with  one  eye  the  blue  part  deviates  to 
one  side  and  the  red  to  the  other  side.  "  By  covering  either  eye  alternately 
a  deviation  of  the  red  and  blue  parts  in  opposite  directions  will  be  observed  ; 
and  on  both  eyes  being  used,  the  notion  of  a  difference  in  distance  is  proved 
by  the  combination  of  the  two  images  in  such  a  way  that  the  parts  that 
deviate  to  the  nasal-side  constitute  the  nearer  image,  the  parts  that  deviate 
to  the  temporal  side,  the  further  image."  Einthoven  finds  that  the  stereo- 
scopic effect  is  more  marked  with  the  coloured  letters. 

(c.)  The  relative  removal  of  the  differently  coloured  images  is  due  to  the 
excentricity  of  the  pupil.  The  pupils  may  be  made  highly  excentric  by 
covering  them  partially.  With  a  nasal  excentric  pupil  {i.e.,  covered  on  the 
temporal  side)  a  shifting  of  the  differently  coloured  images  in  one  direction 
will  be  observed  ;  with  a  temporal  excentric  pupil  {i.e.,  nasal  side  covered) 
the  shifting  will  be  in  the  other  direction. 

Let  any  one  who  sees  the  red  letters  before  the  blue  "cover  his  pupils 
symmetrically  on  the  temporal  side,  the  red  letters  retreat  and  soon  appear  to 
be  behind  the  blue.  On  covering  the  pupils  symmetrically  on  the  nasal  side, 
the  red  letters  come  forward  more  and  more." 

The  bearing  of  these  experiments  is  fully  discussed  by  Einthoven  in  the  paper 
already  referred  to. 

17.  Benham's  Spectrum  Top. 

{a. )  A  cardboard  circular  disc,  about  4  inches  in  diameter,  is  made  with  one 
half  black  and  the  other  half  white.  On  the  white  are  a  number  of  arcs  of 
concentric  circles  of  dirierent  radius.  On  rotating  this  disc,  coloured  lines  are 
seen  whose  order  is  reversed  when  the  disc  is  made  to  rotate  in  an  opposite 
direction.     The  experiment  is  best  performed  by  artificial  light. 

{b.)  Modifiication  by  Hurst. 

On  a  circular  disc,  4  or  5  inches  in  diameter,  half  white  and  half  black, 
draw  in  black  on  the  white  half  and  in  white  on  the  black  half  arcs  of  various 
lengths  and  thicknesses,  as,  for  instance,  the  arcs  shown  in  fig.  283.  Mount 
the  disc  on  a  peg  and  spin  it.  The  arcs  appear  as  circles  of  various  colours, 
the  colour  of  each  depending  on  its  position  and  length,  on  the  velocity  of 
rotation,  and  on  the  kind  and  intensity  of  illumination.  The  two  outermost 
lines  on  the  disc  figured  when  the  disc  is  turned  to  the  left  and  seen  in  very 
bright  lamp-light  appear  purple-grey,  becoming,  as  the  rotation  becomes 
slower,  brighter  and  redder,  and  then  in  succession  bright  crimson,  scarlet, 
and  orange-vermilion.  By  very  bright  direct  sunlight  the  earlier  shades  are 
brighter  than  the  later  ones,  the  colour  being  at  first  usually  a  very  pure  blue. 
When  the  disc  is  turned  to  tlie  right,  the  colours  are  in  succession  dark  green, 
indigo  fringed  witli  pale  blue,  black,  by  lam])light,  while  by  bright  sunlight 
the  colour  is  first  dull  red,  tlien  brown,  and  finally  dark  blue.  They  appear, 
hoAvever,  very  different  to  different  observers. 

The  colours  of  the  white  lines  are  almost  entirely  yellow,  orange-pink,  puce, 
and  "  electric  blue." 

If,  instead  of  arcs  of  circles,  a  spiral -line  ia  drawn  as  in  fig.  284,  the  disc 
exhibits,  when  spun  at  a  suitable  speed,  a  broad  oand  of  colour,  consisting  of 


LXXIV.]  SPECTRUM  TOP.  363 

a  complete  series  of  all  the  colours  of  the  spectrum  in  their  normal  order,  red 
being  on  the  outer  and  violet  on  the  inner  side  of  the  band  when  the  disc  is 
turned  to  the  left,  and  in  the  reverse  order  when  it  is  turned  to  the  right. 
The  purity  of  the  colours  seen  depends  very  greatly  on  the  light  used.  With 
bright  daylight  no  trace  of  a  spectrum  is  seen,  but  a  series  of  colours  ranging 
from  purple  through  brown  to  green,  or  other  series  according  to  intensity  of 
light  and  velocity  of  rotation.  Ev6n  under  the  best  conditions,  namely, 
bright  lamp-light,  slow  rotation,  and  the  eyes  too  fatigued  to  follow  the  line 
round  or  sufficiently  practised  to  remain  motionless,  the  colours  are  not  all 
brightest  at  the  same  moment.  The  violet  has  merged  into  black  before  the 
rotation  has  become  slow  enough  to  give  the  brightest  red  and  orange. 

Beyond  the  limits  of  the  spectrum-coloured  band  are  two  fringes,  a  purple 
or  violet  one  beyond  the  red,  and  luminous  pale  blue  on  the  violet  side.     These 


FlQS.  283  and  284.— Modifications  of  Discs  for  Benham's  Spectrum  Top  (Hurst). 

fringes,  as  well  as  the  spectral  band,  change  somewhat  in  colour  as  the  speed  ol 
rotation  changes. 

The  spiral  is  most  easily  drawn  with  a  brush  full  of  black  paint,  by  draw- 
ing it  lightly  across  a  rotating  white  disc  while  the  disc  is  spinning.  A  suit- 
able portion  of  the  curve  is  chosen  and  the  other  half  of  the  disc  is  blacked. 
Dull  black  ])aint,  such  as  water-colour  "  lamp-black,"  is  best. 

A  very  different  colour-band  is  ])roduced  by  a  similarly  shaped  si)iral  curve 
of  white  drawn  on  the  black  half  of  the  disc.  The  colours  are  "  electric  "  blue, 
})ink,  yellow,  the  blue  being  outermost  when  the  disc  is  spun  to  the  left. 
Spirals  of  various  '  pitches  "  may  be  used,  the  line  itself  being  not  more  than 
one-fifth  of  the  breadth  of  the  space  between  two  successive  turns  of  the  spiral, 
— {Communicated  hij  C.  Herbert  Hurst,  Ph.D.) 

The  appearances  presented  when  the  tops  are  viewed  in  monochromatic  light 
are  quite  as  surprising  as  those  described  above  (see  Abney,  Nature,  vol.  51, 
p.  292,  1895). 

18.  Anaglyph. 

The  pictures  of  one  object  are  printed  on  one  card  in  different  colours,  say 
pale  red  and  blue.  The  two  pictures  are  slightly  displaced  relative  to  each 
other.  On  looking  at  the  picture  through  a  blue  and  a  red  glass,  i.e.,  a  blue 
glass  in  front  of  one  eye,  and  a  red  one  in  front  of  the  other,  one  sees  a  nearly 
colourless  object,  but  the  whole  is  stereoscopic. 


y54  PRACTICAL  PHYSIOLOGY.  [LXiV. 


LESSON  LXXV. 

OPHTHALMOSCOPE— INTRAOCULAR  PRESSURE— 
PICK'S  OPHTHALMOTONOMETER. 

The  Ophthalmoscope. — Two  methods  are  employed,  and  the 
student  must  familiarise  himself  with  both,  by  examining  the  eye  of 
another  person,  or  that  of  a  rabbit,  or  an  artificial  eye. 

1.  Direct — givmg  an  upright  image. 

2.  Indirect — giving  an  inverted  image. 

A.  Human  Eye. — (i.)  Direct  Method. 

(a.)  About  twenty  minutes  before  the  examination  is  commenced, 
instil  a  drop  of  solution  of  sulphate  of  atropine  (2  grains  to  the 
ounce  of  water)  into,  say,  the  right  eye  of  a  person  with  normal 
vision.  The  pupil  is  dilated  and  accommodation  for  near  objects 
is  paralysed,  owing  to  the  paralysis  of  the  cihary  muscle.  The 
patient  is  seated  in  a  darkened  room,  and  the  observer  seats  himself 
in  front  of  him,  and  on  a  slightly  higher  level.  Place  a  brilliant 
light,  obscured  everywhere  except  in  front,  on  a  level  with  the  left 
eye  of  the  patient. 

(b.)  The  observer  takes  the  ophthalmoscope  mirror  in  his  right 
hand,  resting  its  upper  edge  upon  his  eyebrow,  holds  it  in  front  of 
his  own  eye,  looking  through  the  central  hole  in  it,  and  directs  a 
beam  of  Ught  into  the  observed  eye,  when  a  red  glare — the  reflex 
— is  observed.  The  patient  is  told  to  look  upwards  and  inwards, 
which  is  conveniently  accomplished  by  telling  liim  to  look  to  the 
little  finger  of  the  operator's  right  hand.  The  operator  then 
moves  the  mirror,  with  his  eye  still  behind  it,  and  looks  through 
the  hole  until  the  mirror  is  within  two  to  three  inches  from  the 
observed  eye,  taking  care  all  the  time  that  the  beam  of  light  is 
kejjt  steadily  thrown  into  the  eye.  If  the  eyes  of  the  observer 
and  patient  be  normal,  the  observer  has  simply  to  relax  his 
accommodation,  i.e.,  look  as  it  were  at  a  distant  object,  when  the 
retina  comes  into  view  as  an  erect  or  upright  object. 

(c.)  Observe  the  ndinal  blood-vessel s  running  in  different  direc- 
tions on  a  red  ground.  Move  the  mirror  about  to  find  the  optic 
disc,  with  the  central  artery  emerging  from  it.  Trace  the  course 
of  the  veins  accompanying  the  arteries  across  the  disc. 

(2.)  The  Indirect  Method,  giving  an  inverted  image. 

(a.)  The  patient,  the   hght,  and   the   observer   are   as   before. 


LXXV.]  OPHTHALMOSCOPE.  365 

The  observer  places  liimself  ahout  20  to  18  inches  from  the  patient, 
and,  holding  the  mirror  in  his  right  hand,  by  means  of  it  throws 
a  beam  of  light  into  the  eye  of  the  patient.  When  the  eye  is 
illuminated,  he  takes  a  small  biconvex  lens  of  2  to  3  inches  focus 
in  his  unemployed  hand — the  left  in  this  case — holding  it  between 
his  thumb  and  index-finger,  placing  it  vertically  2  or  3  inches  from 
the  observed  eye.  To  ensure  that  the  lens  is  held  steadily,  rest  the 
little  finger  upon  the  temple  or  forehead  of  the  patient.  Keep  the 
lens  steady,  and  move  the  mirror  until  the  optic  disc  is  seen,  with 
the  details  already  described. 

In  the  direct  method  only  a  small  part  of  the  retina  is  seen  at 
one  time,  but  it  is  considerably  magnified  ;  while  by  the  indirect 
method,  although  more  of  the  retina  is  seen  at  once,  it  is  magni- 
fied only  sHghtly. 

If  the  observed  or  observer's  eye  is  abnormal,  suitable  glasses  to 
be  fixed  behind  the  mirror  are  supplied  with  every  ophthalmoscope. 
In  some  forms  of  ophthalmoscope,  /» 

such  as  that  of  Gowers  and  others,  If'  ^_:=^-===i\ 

these  lenses  (convex  + ,  and  con-  ^iLNr"'^"^'     -  ^  v    I  \v 

cave    - )  are  fixed  to  a  rotating  xvWiP'  --^-^^ 

disc  behind  the  mirror.     As  the  ^-^Pl', 

disc  is  rotated,  lens  after  lens  can    ^  /^'"^^i^^^illillllilliilili^ 
be  brought  to  He  exactly  behind    '»i2-'^il|l^  i 
the  hole  in  the  mirror,  and  thus      ^^Bffl  I      1 1111111 
correct  any  anomaly  of  refraction.  ^ffl||ip||^^ 

3.    Eye  of  a  Living  Rabbit.  Fiq.  28 5, -carriage  for  Rabbit. 

Instil  atropine  as  before,  or 
use  an  atropinised  gelatine  disc  to  effect  the  same  result.  Place 
the  rabbit  in  a  suitable  cage  to  keep  it  from  moving.  A  suitable 
one  was  devised  by  ^Michel ;  use  it  (fig.  285).  Examine  the  eye  by 
the  direct  and  indirect  methods.  N.B. — If  an  albino  rabbit  be 
used  the  observer  sees  the  large  choroidal  vessels. 

4.  Perrin's  Artificial  Eye. 

Use  this  until  a  clear  image  of  the  fundus  is  obtained  by  both  methods. 
In  fact,  it  is  well  for  the  student  to  begin  with  this.  In  this  model,  eye-caps 
to  fit  on  to  the  eye  are  supplied,  so  as  to  render  the  eye-model  eitlier  myopic 
or  hypermetropic.  Afterwards  test  these,  and  use  the  necessary  lenses  behind 
the  mirror  to  correct  these  errors  in  the  shape  of  the  eyeball. 

Frost's  artificial  eye,  as  made  by  Curry  and  Paxtou,  is  also  useful,  as  is  also 
that  of  Priestley  Smith. 

5.  Kiihne's  Method. — If  an  artificial  eye  is  not  at  hand,  a  very 
suitable  arrangement  is  that  devised  by  Kiihne.  Paint  a  disc  to 
resemble  the  normal  fundus  when  it  is  seen  with  the  ophthalmO' 


366 


PRACTICAL   PHYSIOLOGY. 


[LXXV. 


scope.  Remove  the  eye-piece — long  one — from  an  ordinary  micro- 
scope. Screw  out  the  lower  lens  of  the  eye-piece,  fix  in  the  painted 
disc,  and  block  up  the  lower  aperture  with  a  piece  of  cork.  Fix 
the  eye-piece  in  a  suitable  holder,  and  use  it  instead  of  an  eye  to  be 
examined. 

6.  Demonstrating  Ophthabnoscope  {Priestley  Smith). 

The  general  arrangement  of  this  instrument  is  shown  in  fig.  286.  At  one 
end  of  the  horizontal  bar  is  a  chin  support  for  the  patient  ;  at  the  other  a 
perforated  glass  mirror,  capable  of  steady  adjustment  to  any  position.  The 
transverse  arm  near  to  the  mirror  carries  a  candle,  provided  with  alight  metal 
screen  on  either  side  of  it ;  one  of  these  hides  the  candle  from  the  patient,  the 
other  hides  it  from  the  observer,  and  enables  him  at  any  moment  to  cut  off 
the  light  from  the  mirror,  and  thus  to  protect  the  patient's  eye  from  unnec^a- 


Demoustrating  Ophthalmoscope.    Made  by  Pickard  and  Curry.     Cost,  £3, 10a. 


sary  illumination  without  disturbing  the  adjustment  of  the  instrument.  A 
wire  placed  in  the  pillar  of  the  mirror,  and  movable  to  either  side,  carries  a 
piece  of  white  paper,  which  serves  as  a  fixation  point  for  the  patient's  eye. 
At  the  middle  point  of  the  horizontal  bar  is  a  jointed  supj)ort  carrying  a  light 
rod,  one  end  of  which  is  held  in  the  hand  of  the  observer,  while  the  other  holds 
the  lens.  By  means  of  this  rod  the  observer  can  place  the  lens  in  any  desired 
position  in  relation  to  the  patient's  eye. 

(i.)  Arrange  the  instrument  as  in  fig.  2S6. 

(2.)  Adjust  the  patient's  seat  so  as  to  bring  his  chin  comfortably  on  the 
support ;  let  him  rest  his  arms  upon  the  table. 

(3.)  Place  the  rod  quite  horizontal,  and  then  raise  or  lower  the  central 
•U].port  until  the  centre  of  the  lens  is  on  a  level  with  the  patient's  pupil. 

(4.)  Push  the  lens  to  one  side  and  adjust  the  mirror  so  as  to  throw  the  light 


LXXVI.]  TOUCH,   SMELL,  TASTE,   HEARING.  367 

upon  the  patient's  eye,  telling  him  to  look,  not  cU  the  mirror^  but  at  the  paper 
placed  upon  the  wire.     The  paper  must  be  on  the  opposite  side  to  the  eye. 

(5.)  Take  the  rod  in  the  hand  and  adjust  the  position  of  the  lens  so  as  to 
bring  the  optic  disc  into  view. 

(6. )  In  changing  places  with  another  observer,  cut  oflf  the  light  from  the 
mirror  by  means  of  the  can  die -screen. 

7.  Intraocular  Pressure, — Pick's  Ophthalmotonometer. 

This  instrument  is  extensively  used  in  German  eye-hospitals,  and  consists  ot 
a  small  brass  plate  (6  mm.  diameter),  which  is  attached  by  means  of  a  metallic 
spring  to  a  base,  which  also  carries  a  scale  which  indicates  the  amount  of 
pressure  applied.  One  presses  the  disc  of  the  instrument  against  the  eyeball 
until  it  flattens  the  part  to  which  it  is  applied,  when  the  pressure  is  read  off 
in  grammes.  The  experiment  may  be  done  first  on  a  rabbit,  as  most  of  them 
remain  quite  passive.  Place  a  person  with  his  left  shoulder  next  the  window, 
ask  him  to  turn  his  eyeballs  to  the  right  and  open  his  eyelids,  whereby 
suflBcient  of  the  eyeball  is  made  visible  for  the  application  of  the  instrument. 

8.  The  Pupil.  —Normally  the  pupil  in  man,  rabbits,  and  other  animals  is 
black,  but  in  albinos  it  is  reddish.   Why  ? 

(i.)  Select  an  albino  rabbit,  and  exactly  in  front  of  its  pupil  hold  up  a  black 
card  with  a  hole  in  it  the  size  of  the  pupil.  Direct  the  pupil  to  the  light,  and 
arrange  the  shade  so  that  all  light  is  kept  from  the  eye  except  that  which 
enters  it  by  the  pupil.     The  albino  pupil  then  appears  black. 

This  shows  that  the  blackness  of  the  pupils  is  not  due  to  the  light 
entering  the  eyeball  being  absorbed  by  the  pigment  of  the  fundus  of  the  eye, 
but  that  light  entering  the  eye  can  only  emerge  by  the  pupil  when  the  iris  and 
the  neighbouring  parts  of  the  choroid,  in  virtue  of  their  pigmentation,  do  not 
permit  light  to  pass  through  them.  The  construction  of  the  dioptric  apparatus 
of  the  eye  is  such  that  light  from  the  fundus  of  the  eye  must  be  reflected  back 
to  the  source  from  which  it  came,  i.e.,  to  the  focus.  As  we  emit  no  light  from 
our  Qje  none  can  come  to  us  from  the  observed  eye,  so  we  see  the  pupil  black 
oecause  we  do  not  illuminate  the  fundus  with  our  body  {Schenk), 


LESSON  LXXVL 
TOUCH —SMELL— TASTE— HEARING. 

1.  Touch — The  Sense  of  Locality. 

(a.)  Ask  a  person  to  shut  his  eyes,  touch  some  part  of  his  hody 
with  a  pin,  and  ask  him  to  indicate  the  part  touched. 

(//.)  ^sthesiometer.— -Use  a  small  pair  of  wooden  compasses, 
or  an  ordinary  pair  of  dividers  with  their  points  guarded  by  a 
small  piece  of  cork,  or  Sieveking's  ^sthesiometer.  Apply  hghtly 
the  points  of  the  compasses  simultaneously  to  different  parts  of 
the  body,  and  ascertain  at  what  distance  apart  the  points  are  felt 
as  two.     The  following  is  the  order  of  sensibihty  : — Tip  of  tongue 


368 


PRACTICAL   PHYSIOLOGY. 


[lxxvl 


(i.i  mm.),  tip  of  the  middle  finger  (2.3),  palm  (8  to  9),  forehead 
(22),  back  of  hand  (31.6),  back  (66). 

(t:.)  Test  as  in  (h.)  the  skin  of  the  arm,  beginning  at  the  shoulder 
and  passing  downwards.  Observe  that  the  sensibility  is  greater  as 
one  tests  towards  the  fingers,  and  also  in  the  transverse  than  in  tho 
long  axis  of  the  limb.  In  all  cases  compare  the  results  obtained  on 
both  sides  of  the  body. 

(d.)  By  means  of  a  spray -producer  spray  the  back  of  the  hand  with  ether, 
and  observe  how  the  sensibility  is  abolished. 

(e.)  V.  Frey's  Method.— A  hair  of  the  head  or  beard  (20-40  mm.  long)  is 
fixed  to  a  wooden  match.  On  pres.sing  tlie  point  of  the  hair  against  the  skin 
it  may  or  may  not  be  felt  as  a  tactile  sensation.  This  depends  on  the  pressure 
exerted  on  the  hair,  and  this  in  turn  on  the  sectional  area  and  stiffness  of  the 
hair  itself.  One  can  measure  the  pressure  exerted  by  pressing  the  hair  on  a 
balance  and  from  the  sectional  area  of  the  hair  deduce  the  pressure  per  sq. 
mm.  According  to  v.  Frey  the  sensibility  of  the  cornea  and  conjunctiva  is 
distributed  in  a  punctiform  manner,  insensible  areas  existing  between  :  pain 
alone,  according  to  v.  Frey,  being  experienced  from  stimulation  of  the  cornea 
with  the  exception  of  its  margin  and  the  teeth,  or  rather  the  dentine  and  pulp. 
(V.  Frey,  "  Beitrrige  z.  Physiologie  d.  Schmerzsinns,"  and  "Beit.  z.  Sinnes- 
j)hysiologie  d.  Haut,"  Be  rich.  a.  d.  math.-phys.  Classe  d.  Konigl.  Sachs. 
Gesell.  d.  Wissen.  Leipzig,  Dec.  1894,  and  March  1895.  Criticism  by  Nagel, 
Ffliigey^s  Archiv,  Bd.  59,  p.  563,  1895.) 

(J.)  Illusions — Aristotle's  Experiment. — Cross  the  middle  over 
the  index-finger,  as  in  fig.  287,  roll  a  small  ball  between  the 
fingers ;  one  has  a  distinct  impression  of  two 
balls.  Or,  cross  the  fingers  in  the  same  way, 
and  rub  them  against  the  point  of  the  nose. 
The  same  illusion  is  experienced. 

2.  The  Sense  of  Temperature. 

{a.)  Ask  the  person  experimented  on  to 
close  his  eyes.  Use  two  test-tubes,  one  filled 
with  cold  and  the  other  with  hot  water,  or 
two  spoons,  one  hot  and  one  cold.  Apply  one 
or  other  to  different  parts  of  the  surface,  and 
ask  the  person  to  say  whether  the  touching 
body  is  hot  or  cold.  Test  roughly  the  sensi- 
bility of  diff'erent  parts  of  the  body  with  cold 
and  warm  metallic-pointed  rods. 
(6.)  Touch  fur,  wood,  and  metal.  The  metal  feels  coldest, 
although  all  the  objects  are  at  the  same  temperature. 

{r. )  Plunge  the  hand  into  water  at  36°  C.  One  experiences  a  feeling  of  heat. 
Then  })lunge  it  into  water  at  30°  C,  at  first  it  feels  cold,  because  heat  is 
abstracted  from  the  hand.  Plunge  the  other  hand  direct  into  water  at 
30°  C.  without  previously  placing  it  in  water  at  36°  C,  it  will  feel  pleasantly 
warm. 


Fig.  287. 


LXXVT.]  TOUCH,   SMELL,  TASTE,   HEARING.  369 

(d.)  Hold  one  hand  for  a  time  in  water  at  10"  C,  and  afterwards  place  it 
in  water  at  20°  C,  at  first  the  latter  causes  a  sensation  of  heat,  which  soon 
gives  place  to  that  of  cold. 

(^.)  Test  with  the  finger  the  acuteness  of  the  sense  of  temperature,  i.e.,  in 
two  given  fluids  of  ditierent  temperatures,  what  fraction  of  a  degree  C.  can  be 
distinguished.  One  can  usually  distinguish  |°,  although  the  acuteness  is 
greater  when  the  fluids  are  about  30"  C. 

if.)  Use  two  brass  tubes  (5  cm.  long  and  i  cm.  in  diam.),  terminating  in  a 
point.  Cover  both,  all  except  the  point,  with  india-rubber  tubing.  Fill  one 
with  warm  water  and  the  other  with  cold.  Test  the  j)osition  of  the  warm  and 
cold  points  on  another  person  on  various  parts  of  the  skin. 

(7.)  Warm  and  Cold  Spots. 

With  a  blunt  metallic  point  touch  different  parts  of  the  skin. 
Certain  points  excite  the  sensation  of  warmth,  others  of  cold, 
although  the  temperatures  of  the  skin  and  the  instrument  remain 
constant.  Map  the  position  of  the  cold  and  hot  spots  by  means  of 
different  colours. 

3.  Sense  of  Pressure. 

(rt.)  Rest  the  back  of  the  hand  on  a  table,  cover  a  small  area  of 
the  palm  with  a  non-conducting  material,  e.g.,  a  wooden  disc.  On 
the  latter  place  different  weights.  Estimate  the  smallest  difference 
of  weight  which  can  be  appreciated. 

(&.)  Dip  the  hand  or  a  finger  into  mercury.  The  greatest  sensation  is  felt 
at  the  plane  of  the  fluid  in  the  form  of  a  ring,  but  even  this  is  best  felt  on 
moving  the  hand  up  and  down. 

4.  Peripheral  Projection. 

(a.)  Press  the  ulnar  nerve  at  the  elbow,  the  prickling  feeling  is 
referred  to  the  skin  on  the  ulnar  side  of  the  hand.  . 

{b.)  Dip  the  elbow  in  ice-cold  water  ;  at  first  one  feels  the  sensation  of  cold 
owing  to  the  effect  on  the  cutaneous  nerve-endings.  Afterwards,  when  the 
trunk  of  the  ulnar  nerve  is  affected,  the  pain  is  felt  in  the  skin  of  the  ulnar 
side  of  the  hand  where  the  nerve  terminates. 

5.  Reference  of  Tactile  Impressions  to  the  Exterior. — Gene- 
rally speaking,  the  sensation  of  touch  is  referred  to  our  cutaneous 
surfaces.  In  certain  cases,  however,  it  is  referred  even  beyond 
this. 

(a.)  Holding  firmly  in  one  hand  a  cane  or  a  pencil,  touch  an 
object  therewith  ;  the  sensation  is  referred  to  the  extremity  of  the 
cane  or  pencil. 

(b.)  If,  however,  the  cane  or  pencil  be  held  loosely  in  one's  hand, 
one  experiences  two  sensations,  one  corresponding  to  the  object 
touched,  and  the  other  due  to  the  contact  of  the  rod  with  the  skin. 
The  process  of  mastication  affords  a  good  example  of  the  reference 
of  sensations  to  and  beyond  the  periphery  of  the  body. 

2  A 


370  PRACTICAL   PHYSIOLOQY.  [LXXVI. 

6.  Sense  of  Contact. 

Touch  your  forehead  with  your  forefinger,  the  finger  appears 
to  feel  the  contact ;  but  on  rubbing  the  forefinger,  or  any  other 
digit,  rapidly  over  the  forehead,  it  is  the  latter  which  is  interpreted 
as  "  feeling  "  the  finger. 

7.  Weber's  Circles. 

Cut  short  lengths  from  glass  tubing  of  various  sizes,  varying  from 
a  quarter  of  an  inch  to  two  inches  or  more  in  diameter,  and  provide 
glass  vessels  of  similar  size,  each  with  a  glass  base.  Press  tlie 
smaller  circles  and  corresponding  size  of  vessel  on  the  cheek  and 
forehead  and  the  larger  ones  on  the  thorax  or  abdomen.  It  is 
impossible  when  the  eyes  are  shut  to  determine  whether  a  closed 
or  open  vessel  is  pressed  on  the  skin.  The  size  of  the  vessel  to 
obtain  this  result  varies  with  the  cutaneous  surface  experimented 
on. 

8.  niusions. 

{n.)  Place  a  thin  disc  of  cold  lead  the  size  of  a  florin  on  the  foreheed  of  a 
person  whose  eyes  are  closed,  remove  the  disc,  and  on  the  same  spot  place 
two  warm  discs  of  equal  size.  The  person  will  judge  the  latter  to  be  about 
the  same  weight,  or  lighter,  than  the  single  cold  disc. 

(b.)  Compare  two  similar  wooden  discs,  and  let  the  diameter  of  one  be 
slightly  greater  than  that  of  the  other.  Heat  the  smaller  one  to  over  50°  C, 
and  it  will  be  judged  heavier  than  the  larger  cold  one. 

(c-.)  Lay  on  different  parts  of  the  skin  a  small  square  piece  of  paper  with  a 
small  central  hole  in  it.  Let  the  person  close  his  eyes,  while  another  person 
gently  touches  the  uncovered  piece  of  skin  with  cotton  wool,  or  brings  near  it 
a  hot  body.  In  each  case  ask  the  observed  person  to  distinguish  between 
them.  He  will  always  succeed  on  the  volar  side  of  the  hand  but  occasionally 
fail  on  the  dorsal  surface  of  the  hand,  the  extensor  surface  of  the  arm,  and 
very  frequently  on  the  skin  of  the  back. 

((/.)  Estimation  of  the  distance  of  two  neighbouring  parts  depends  on  the 
size  of  the  sensory  circles.  If  the  points  of  a  pair  of  compasses  about  i  cm. 
apart  are  placed  on  the  skin  in  front  of  the  ear  and  moved  towards  the  lips, 
the  points  feel  as  if  they  diverged. 

9.  The  Muscular  Sense. 

(a.)  "With  the  arm  and  hand  unsupported,  the  eyelids  closed,  and  the  same 
precautions  as  in  3  {a.),  determine  the  smallest  difference  which  can  he  per- 
ceived between  two  weights.  It  will  be  less  than  in  cartridges  filled  with  a 
known  weight  of  shot,  and  tested  by  the  pressure-sense  alone.  The  cartridges, 
e.g.,  100  grms.,  are  numbered,  and  they  are  so  made  as  to  have  a  small  increas- 
ing increment  of  weight.     They  are  alike  in  external  a{)pearance. 

{b. )  Take  two  equal  iron  or  lead  weights,  heat  one  and  leave  the  other  cold. 
The  cold  one  will  feel  the  heavier. 

10.  Taste  and  SmeLL — Prepare  a  strong  solution  of  sulphate  of 
quinine,  with  the  aid  of  a  Httle  sulphuric  acid  to  dissolve  it  (bitter), 


lxxvl]  touch,  smell,  taste,  hearing.  371 

a  5  per  cent,  solution  of  sugar  {swept),  a  10  per  cent,  solution  of 
common  salt  {saline),  and  a  i  per  cent,  solution  of  acetic  acid 
{acid), 

{a.)  Wipe  the  tongue  dry,  lay  on  its  tip  a  crystal  of  sugar.  It 
is  not  tasted  until  it  is  dissolved. 

{h.)  Apply  a  crystal  of  sugar  to  the  tip  and  another  to  the  back 
of  the  tongue.     The  sweet  taste  is  more  pronounced  at  the  tip. 

(c.)  Repeat  the  process  with  sulphate  of  quinine  in  solution.  It 
is  scarcely  tasted  on  the  tip,  but  is  tasted  immediately  on  the  back 
part  of  the  tongue. 

(tZ.)  Test  where  salines  and  acids  are  tasted  most  acutely. 

{e.)  Connect  two  zinc  terminals  with  a  large  Grove's  battery,  ap])ly  them  to 
the  upper  and  under  surface  of  the  tongue,  and  pass  a  constant  current  through 
the  tongue.  An  acid  taste  will  be  felt  at  the  positive,  and  an  alkaline  one  at 
the  negative  pole. 

(/. )  Close  the  nostrils,  shut  the  eyes,  and  attempt  to  distinguish  by  taste 
alone  between  an  apple  and  a  potato. 

(g.)  Gymnema  Sylvestre, — Use  a  5  p.c.  decoction  of  the  leaves  and  apply 
it  to  limited  areas  of  the  tongue  by  means  of  a  camel-hair  pencil.  In  20-30 
seconds  wash  out  the  mouth  and  then  test  the  action  of  glycerin  (5-10  p.c), 
quinine  (i  p.c.  with  .01  p.c.  of  H.SOj*,  H2SO4  (.05  p.c),  NaCl  (.5  p.c). 

The  sweet  and  bitter  tastes  are  readily  prevented  in  all  regions  ;  but  acid 
and  saline  tastes  are  not  influenced  (L.  E.  Shore,  "  A  Contribution  to  our 
Knowledge  of  Taste  Sensations,"  Journ,  of  Phys.,  xiii.  p.  191).  It  has  no  effect 
on  tactile  sensations. 


11.  Ear.     Hearing. 

(a.)  Hold  a  ticking  watch  between  your  teeth,  or  touch  the 
upper  incisors  with  a  vibrating  tuning-fork,  close  both  ears,  and 
observe  that  the  ticking  is  heard  louder.  Unstop  one  ear,  and 
observe  that  the  ticking  is  heard  loudest  in  the  stopped  ear. 

{h.)  Hold  a  vibrating  tuning-fork  on  the  incisor  teeth  until  you 
cannot  hear  it  sounding.  Close  one  or  both  ears  and  you  will  hear 
it. 

{a.)  Listen  to  a  ticking  watch  or  a  tuning-fork  kept  vibrating 
electrically.  Close  the  mouth  and  nostrils,  and  take  either  a  deep 
inspiration  or  deep  expiration  so  as  to  alter  the  tension  of  the  air 
in  the  tympanum ;  in  both  cases  the  sound  is  diminished. 

(r/.)  Connect  two  telephones  in  circuit  with  a  vibrating  beef's 
hammer  of  an  induction  machine,  and  place  a  telephone  to  each 
ear ;  one  hears  the  sound  as  if  it  came  from  within  one's  own  head 
in  the  vertical  median  plane. 

{e,)  With  a  blindfolded  person  test  his  sense  of  the  direction  of 
sound,  e.g.,  by  clicking  two  coins  together.  It  is  very  imperfect. 
Let  a  person  press  both  auricles  against  the  side  of  the  head,  and 
hold  both  hands  vertically  in  front  of  each  meatus.     On  a  person 


372  PRACTICAL   PHYSIOLOGY.  [LXXVI 

making  a  sound  in   front,   the  observed  person   will   refer  it  to  a 
position  beliind  him. 

(/'.)  Test  the  highest  audible  sound  by  means  of  Galton's 
whistle. 

12.  Dissection  of  the  Middle  Ear. — It  is  most  important  for  the 
student  to  do  this.  Use  the  head  of  a  sheep.  Remove  the  lower 
jaw,  expose  the  temporal  bulla.  Open  this  and  thus  reach  the 
tympanic  cavity,  when  the  various  structures  situated  in  the 
middle  ear  are  readily  brought  into  view. 

13.  Influence  of  Excitation  of  one  Sense-Organ  on  the  other 
Sense-Organs. — Urbantschitsch  has  made  a  large  number  of 
experiments  on  this  subject. 

{a.)  Small  coloured  patches  whose  shape  and  colour  are  not  distinctly  visible 
may  become  so  when  a  tuning-fork  is  kept  vibrating  near  the  ears.  In  other 
individuals  the  visual  impressions  are  diminished  by  the  .same  process. 

(b.)  On  listening  to  the  ticking  of  a  watch,  the  ticking  sounds  feebler  or 
stronger  on  looking  at  a  source  of  light  through  glasses  of  different  colours. 

(c.)  If  the  finger  be  placed  in  cold  or  warm  water  the  temperature  appears 
to  rise  when  a  red  glass  is  held  in  front  of  the  eyei. 


APPENDIX, 


SOME  WOKKS  USEFUL  IN  THE  LABORATORY. 

E.  Gscheidlen,  Physiologische  Methodik,  1876  (incomplete). — E.  Cyon, 
Methodik  der  physiologischen  Experimente  u.  Vivisektionen,  with  Atlas, 
1876  (only  one  part  issued). — Ott,  The  Actions  of  Medicines,  Pliil,,  1878. — 
Claude  Bernard  and  Huette,  Precis  iconograpliique  de  mcdecine  operatoire  et 
d'anatomie  chirurgicale,  with  113  plates,  1873  ;  also  Lecons  de  physiologic 
operatoire  (edited  by  Duval),  Paris,  1879. — Sanderson,  Foster,  Klein,  and 
Brunton,  Handbook  for  the  Physiological  Laboratory  (Text  and  Atlas).  The 
French  edition  contains  additional  matter.  —  Meade-Smith,  Trans,  of 
Hermann's  Toxicol. — J.  Burdon- Sanderson,  Practical  Exorcises  in  Physiology, 
London,  1882, — Foster  and  Langley,  Pract.  Phys.,  London,  1884.— B.  Stewart 
and  Gee,  Pract.  Physics.  —  Vierordt,  Anat.  Physiol,  u.  Physik.  Daten  u. 
Tabellen,  Jena,  1888. — ^MUller-Pouillet,  Lehrb.  d.  Physik.,  8th  ed.,  Braunsch- 
weig.— Wiillner,  Lehrb.  d.  exp.  Physik. — Livon,  Manuel  de  Vivisect.,  Paris, 
1882. — Harris  and  Power,  Manual  for  the  Phys.  Lab.,  5th  ed.,  1892. — Straus- 
Durckheim,  Anat.  descrip.  comp.  du.  chat,  Paris,  1845. — W.  Krause,  Die 
Anatomic  des  Kaninchens,  Leipzig,  2nd  ed.,  1883. — A.  Ecker,  Die  Anatomie 
des  Frosches,  1864-1882,  2nd  ed.,  pt.  i.,  1888. — Biolog.  Memoirs,  edited  by 
Burdon-Sanderson. — Helmholtz,  Physiol.  Oi)tik,  2nd  ed. — Hermann,  Hand 
buch  der  Physiologie  (by  various  authors). — Gad,  Real-Lexikon  d.  Med.  Pro- 
padeutik,  Wien,  1893  (not  yet  completed).— L.  Fredericq,  Manipulations  de 
Physiologie,  1892. — Langendorfif,  Physiol.  Graj)hik.— Gotch,  Practical  Exer- 
cises in  Physiology. — Halliburton,  Syllabus  of  Experimental  Lessons,  1893, — 
Schenck,  Physiologisches  Practicum,  Stuttgart,  1895. — W.  Biedennann, 
Elektrophysiologie,  Jena,  1895  (a  most  useful  work,  chiefly  dealing  with 
Muscle  and  Nerve). — Richet,  Dictionnaire  de  Physiologie,  vol.  i.,  Paris,  1895. 

The  above  list  takes  no  account  of  the  various  Physiological  Journals. 


374  APPENDIX. 


SOME  WORKS  OF  REFERENCE   ON  CHEMICAL 
PHYSIOLOGY. 

Hoppe-Seyler,  Physiologische  Chemie,  Berlin,  1892-94.  —  Lelimanii, 
Lehrb.  d.  phys.  Chein.,  3rd  edit.,  Leipzig,  1853  ;  and  Handbuch,  1859. — Leo. 
Liebermann,  Grundziige  der  Chemie  des  Menschen,  Stuttgart,  1880.— Eobin 
and  Verdeil,  Traite  de  chem.  anat.  et  phys.  (with  Atlas),  Paris,  1853.  Thia 
Atlas  contains  beautiful  plates  with  figures,  many  coloured,  of  all  the  most 
important  organic  crystalline  bodies. — A.  Wynter  Blyth,  Foods,  1887.— Gonip- 
Besanez,  Anleitung  zur  Zoo-chemischen  Analyse,  187 1. — Gautier,  Chimie 
applique  a  la  Physiologic,  1874.  —  Lehmann's  Phys.  Chem.  (translated  by 
Cavendish  Soc,  1851-1854),  with  Atlas  of  0.  Funke's  plates.  These  plates 
contain  some  histological  figures,  and  many  coloured  plates  of  blood-crystals, 
deposits  in  urine,  &c. — Kingzett,  Animal  Chem.,  1878. — Thudichmn,  Ann.  of 
Chem.  Med.,  1879. —A.  Gamgee,  Physiological  Chemistry  of  the  Animal 
Body,  vol.  i.,  1880;  vol.  ii..  Chemistry  of  Digestion,  1893. — Hoppe-Seyfer, 
Medicinische  Chemische  Untersuchungen,  Berlin.  This  contains  a  number  of 
special  memoirs  by  the  pupils  of  the  author. — Hoppe-Seyler,  Zeitschrift  flir 
physiologische  Chemie,  Strassburg,  1877,  and  continued  until  the  present. — 
Watts'  Dictionary  of  Chemistry,  second  supplement,  London,  1875. — Ralfe, 
Clinical  Chemistry,  London,  1880;  and  Clinical  Chem.,  1883. — Wurtz,  Traite 
de  chim.  biol.,  Paris,  1880.— Parkas'  Hygiene,  7th  edit. — T.  G.  Charles, 
Physiological  and  Pathological  Chemistry,  London,  1884. — ^Maly's  Jahresb. 
ii.  Thierchemie.  This  gives  a  resurrU  of  the  most  important  memoirs  pub- 
lished during  the  year. — Articles  in  Hermann's  Handbuch  d.  Physiologic, 
1879-18S4,  and  the  various  Text-books  on  Organic  Chemistry. — Eoscoe  and 
Schorlemmer,  (Organic)  Chem.,  1 884-1 889. — Beilstein,  Handb.  d.  organ. 
Chem. — Krukenberg,  Grundriss  d.  med.  chem.  Analyse,  1884.  — MacMunn, 
The  Spectroscope  in  Medicine,  1880  ;  Clinical  Chemistry,  1 890.  — Drechsel, 
Anleit.  z.  Darstell.  phys.  Chem.  Pniparate,  1889. — Ladenburg,  Handworter- 
buch  d.  Chemie.  This  consists  of  special  articles,  and  is  on  the  plan  of 
Watts'  Dictionary  of  Chemistry.  — Kossel,  Leitfaden  fur  med.  chem.  Curse, 
1889. — Rohmann,  Anleitung  z.  chem.  Arbeiten,  1890. — Landolt,  Dasoptisches 
Drehungsvermogen  is  the  standard  work  on  polariscopic  methods. — MacMunn, 
on  the  Spectroscope.  This  work  has  good  lithographed  and  coloured  spectra. 
— Tollens,  Handbuch  d.  Kohlenhydrate,  Breslau,  1883.  This  is  the  best  work 
on  the  Carbohydrates. — Sutton,  Volumetric  Analysis.  This  work  gives  all 
the  most  important  methods  for  this  process. — Bunge,  Phys.  and  Path.  Chem., 
trans,  by  Wooldridge,  1890,  4th  German  ed.,  1894.— V.  Jaksch,  Clinical 
Diagnosis,  trans,  by  Cagney,  2nded. — Halliburton,  Chemical  Phys.  and  Path., 
1891. — Hammarsten,  Lehrb.  d.  Physiol.  Chem.,  2nd  ed.,  Wiesbaden,  1891,— 


APPENDIX.  375 

S.  Lea,  riie  Chemical  Basis  of  the  Animal  Body,  1892. — Salkowski,  Practi- 
cum  d.  phys.  u.  path.  Chemie,  Berlin,  1893. — Annand  Gautier,  Cours  de 
Chemie ;  Chimie  Biologique,  vol.  iii.,  Paris,  1892. — Hempel,  Gas  Analyse, 
translated  by  L,  M.  Dennis. — Neumeister,  Lehrb.  d.  phys.  Chem.,  pt.  i., 
1892. — Chittenden,  Digestive  Proteolysis,  New  Haven,  Conn.,  1895. 

The  literature  on  the  "  Urine  "  is  necessarily  very  large,  and  may  readily  be 
obtained  on  consulting  any  of  the  standard  works  on  that  subject. 

The  following  are  the  CHIEF  JOURNALS  AND  PERIODICALS  containing 
physiological  literature. 

Proceedings  and  Transactions  of  the  Royal  Society. 

Journal  of  Anatomy  and  Physiology  (Humphry,  Turner  &  M'Kendrick) 
from  1868. 

The  Journal  of  Physiology  (Foster,  and  presently  Langley)  since  1878. 

Archivfiir  Anatomie  und  Physiologie  (Miiller  1834-1858,  du  Bois-Reymond 
from  1859. 

Zeitschrift  fiir  Biologic  (Kiihne  &  Voit  from  1865). 

Archiv  fiir  die  gesammte  Physiologie  (Pfliiger  from  1868). 

Archiv  fiir  path.  Auat.  und  Physiologie  (Virchow  from  1847). 

Archiv  fiir  exp.  Path,  und  Pharmacologic  (Naunyn  &  Schmiedeberg  from 

1873)- 

Skandinavisches  Archiv  fiir  Physiologie  (Holmgren  from  1889). 

Zeitschrift  fiir  Physiol.  Chemie  (Hoppe-Seyler  from  1877). 

Sitzungsberichte  der.  Acad.  d.  Wissenschaften,  of  Berlin  from  1836,  of 
Vienna  from  1848. 

Ludwig's  Arbeiten  Leipzig  from  1 866-1 877  (continued  in  du  Bois  Archly 
from  1877). 

Coiiiptes  rendus  de  1'  Acad,  des  Sciences  from  1835. 

Comptes  rendus  de  la  Societe  de  Biologic  from  1850. 

Berichte  d.  deitsch.  chem.  Gesellschaft. 

Journal  de  la  Physiologie  (Brown-Sequard  from  1858-1863). 

Archives  dePhysiologie  (formerly  Brown-Sequard,  now  Bouchard,  Chauyeanx 
&  Marey)  from  1868. 

Journal  de  I'Anat.  et  de  la  Physiol.  (Robin,  Pouchet,  now  Mathias  Duval) 
from  1864. 

Archives  Italiennes  de  Biologie  (Mosso  from  1882). 


GENERAL  REFERENCES  AND  ABSTRACTS. 

Schmidt's  Jahrbucher  (from  1834).  Canstadt's  Jahresbericht ;  Hoffmann 
&  Schwalbe's  Jahresbericht  (from  1873,  now  by  Hermann).  Maly's  Jahres- 
bericht ii.  d.  Fortschritte  d.  Thier  Chemie  (chiefly  physiological  chemistry). 
Hayem,  Revue  des  Sciences  medicales.     Reports  of  the  Chemical  Society. 


.'tJ 


37^ 


APPENDEL 


in 

CARBOHYDRATES 


Q 


\0 


6  ^ 


oo 


Cellulose. 


Starch. 


Glycogen. 


Dextrin. 


Cane-Sugar. 
CioH..,Ou. 


Milk-Sngar. 
C10H22OU+H2O. 


Maltose. 
CioH^iOn  +  HoO. 


Dextrose. 

CeHiaOgC  +  HoO]. 


LaBvnlose. 


Galactose. 
CgHiijO^ 


Solubility. 


Insoluble  in  water, 
dilute  acids,  and 
alkalies ;  soluble 
in  a m m o n i o- 
oxide  of  copper. 


Swells  up  in  water, 
dissolves  in 
warm  water. 


Soluble   in  water, 
opalescent. 


Readily  soluble 
in  water ;  sol- 
uble  with 
difficulty  in 
strong  alcohol. 


Relation  to 

lodo-iodide  ol 

Potassium 

Solution- 


After      treat- 
ment   with 
H2SO4. 
Blue. 


Bine. 


Brown  or  port 
wine. 


Brown. 


-  Uncoloured 


Rotation 
[a]D. 


+    197 


+   3IX 


+  174- S 


+  66.5 


+  52.53 
iiirotation. 


+  140 
Half, 
rotation. 


+  52-74 
Birotation. 


7X.4 


+  80.5 
Birotation. 


iPPENDIX. 


377 


(after  Tollens). 


By  Hydrolysis  on 

Boiling  with    I      Action  of 

Dilute  Acids.    1      Ferments, 

Arises 


Arabinose, 

Galactose,  and 

other  bodies. 


Dextrose. 


Dextrose  and 
Laevulose. 


Dextrose  and 
Galactose. 


Dextrose, 


No  action. 


By  diastase 

into 
Dextrin 

and 
Maltose. 


By  diastase 
slowly  into 
Dextrose. 


By  invertiu 

Dextrose  and 

Laevulose. 


By  ferment  of 
Kefyrs,  Dex- 
trose, and 
Galactose. 


By  diastase 
Dextrose  [?]. 


Yeast  and 
Similar  Fungi. 


No  action. 


'   No  action. 


After  invertin 

ferments  by 

Yeast. 


Ferments 

with 

Kefyrs. 


Fermentation 
by  Yeast, 


Non-fermen- 
tation by 
Yeast 


Reducing 
Power. 


Phenyl-hydrazin 

Compounds. 


Phen  yl-glucosazon. 


5-  §-^ 


M.P. 

-Lactosazon       200° 


-Maltosazon 

206" 

-Glycosazon 

204/5° 

-Laevulosazon 

204° 

-Galactosazon    193" 


378 


APPENDIX. 


BODIES  OF  THE 


The  Aromatio  Compounds  of  the  Urinb  and  thbir 


Tyrosin. 

prr  OH 

^s^^^CHg.  CH.  NHj,.  COOH. 

From  albumin — 

By  trypsin. 

By  putrefaction. 

By  fusing  with  KHO. 

In  urine — 

In  acute  yellow  atrophy 
of  the  liver  and  phos- 
phorus poisoning. 


Phenylamidopropionic 
Acid. 

CgHg.  CH,.  CH .  NH.,.  COOH. 

Decomposition  of  albumin 
in  seedlings. 


Oxyphenyloxypropionic 
Acid. 

[Oxyhydroparacumaric 
acid.l 


C«H 


OH 


■^CHa.CH.OH.COOH. 

In  the  urine  of  the  rabbit 
after  feeding  with  ty- 
rosin. 

In  human  urine,  after 
acute  yellow  atrophy  of 
the  liver  and  phospho- 
rus poisoning. 


Phenylpropionic  Acid. 

CeHj.CHaCHo.COOH. 

Decomposition  product  of 
albumin,  oxidised  in  the 
organism  to 

Benzoic  acid. 

CgHs-COOH. 

which  passes  into  the 
nrine  as 

Hippnric  acid. 
CgHB.CX).NH.CH2.C00H. 


Oxyphenylpropionic  Acid. 
[Hydroparacumaric  acid.] 

'"e^^CHsj.CHaCOOa 

Normal  constituent  of 
urine,  decomposition 
product  of  tyrosin. 
When  given  to  an  ani- 
mal, part  is  excreted 
unchanged,  part  is  oxi- 
dised to 

Paraoxybenzoic  acid. 


C«H 


OH 


«"^COOH 

which  passe.s  into  the 
urine  as 

Paraoxybenzuric  acid. 


C«H 


OH 


«^*CO.NH.CH.,.COOH. 


Phenjlamidoacetic  Acid. 

C6H3.CH.NH2.COOH. 

Yields    during    putrefac- 
tion 

Amygdalic  acid. 
C,H5.CH.0H.C00H. 


APPENDIX. 


379 


AROMATIC  SERIES. 


Relation  to  the  Decomposition  Products  op  Albumin. 


Oxyphenylacetic  Acid. 


an 


OH 


'e'^^CHa-COOH. 

Putrefactive  product  of 
tyrosiu ;  normal  uri- 
nary constituent.  When 
given  to  an  animal,  it 
leaves  the  organism  un- 
changed. 


Phenylacetic  Acid. 

C6H5.CH2.COOH. 

Putrefactive    product     of 
phenylamidoproplonic 
acid    and    of    albumin, 
passes  into  the  urine  as 

Phenaceturic  acid. 

an..CH2.C0.NH.CH2 
COOU. 


Parakresol. 
err  OB. 

Putrefactive  product  of 
ty rosin  ;  occurs  in  urine 
as 

P    TT    CHo 


IndoL 
CH-CH 

Obtained  from  albumin 
by  putrefaction,  and 
heating  with  caustic 
potash. 

In  the  organism  it  is  oxi- 
dised to 

IndoxyL 
C(OH)-CH 

NH' 
Passes  into  the  urine  as 

,  Indoxylsulphuric  acid. 
C(0.S03H)-CB 

NH' 


Phenol. 

C«H..OH. 

Putrefactive  product  of 
tyrosin ;  occurs  in  urine 
as 

CgHg.OSOaOH. 

In  the  organism,  it  is 
partly  oxidised  into 

Pyrocatechin. 

p   ttOH 

'"«"*0H 

which  occurs  as  a  con- 
stituent of  horses'  urine, 
partly  as  an  ether 
sulpho-compound,  and 
partly  free. 


C6H4<( 


Skatol. 
C(CH3)  =  CH 


Putrefactive  product  of 
albumin,  passes  into  the 
urine  as 

(Skatoxylsulphuric  acid). 
C(CH3.0.SOaOH)=CH 

NH 


38c  APPENDIX. 


SOME  PEODUCTS  OF  TEYPTIC  PROTEOLYSIS— LYSIN, 

LYSATIN. 

In  Lesson  X,,  5,  Leucin  and  Ty rosin  are  stated  to  be  products  formed  by  the 
action  of  the  tryptic  enzyme  on  proteids.  These  substances,  as  well  as  others, 
viz.,  aspartic  acid  and  glutamic  acid,  have  long  been  known  as  decomposition 
products  of  vegetable  proteids,  e.g.,  as  cleavage  products  by  boiling  w  th 
dilute  acids.  Aspartic  acid  is  amido-succinic  acid,  COOH.CH2CH(NH2). 
COOH,  and  is  also  a  product  of  pancreatic  digestion  of  fibrin,  while  glutamic 
acid,  COOH.  C3H5(NH2).  COOH,  is  amido-pyrotartaric  acid.  Both  acids 
belong  to  the  fatty  acid  series. 

Drechsel  has  recently  discovered  two  new  nitrogenous  bases — lysin  and 
lysatinin  or  lysatin — products  of  the  decomposition  of  proteids  {e.g.,  casein, 
gelatin,  egg-albumin)  when  the  latter  are  boiled  with  HCl  and  stannous 
chloride.  These  bodies  result  from  the  simple  hydroly  tic  cleavage  of  the  proteid 
molecule,  and  it  has  recently  been  shown  by  Hedin  that  they  are  also  formed 
in  trypsin -proteolysis. 

Lysin,  C6H14N2O2,  is  a  diamido-caproic  acid,  and  is  a  representative  of  the 
fatty  acid  group,  and  has  intimate  chemical  relationships  with  leucin. 

Lysatinin  or  Lysatin,  CgHjaNgO..  —  Its  composition  is  less  accurately  known, 
but  it  has  the  composition  of  a  creatin.  The  special  interest  which  attaches 
to  this  body  is  that,  as  a  product  of  trypsin -proteolysis,  it  can  by  simple 
hydrolytic  decomposition  break  down  into  urea.  Thus  trypsin-proteolysis 
yields  cleavage  products,  from  one  or  more  of  which  conies  the  substance  lysatin, 
which  behaves  like  creatin  in  this  respect,  viz.,  that  when  boiled  with  baryta- 
water,  it  yields  sarkosin  and  urea.  Thus  chemists  have  found  a  series  of 
cleavage  products  the  result  of  hydrolytic  decomposition  between  proteid  and 
urea.  (Chittenden,  Digestive  proteolysis^  p.  103,  New  Haven,  1895.  Cartwright 
Lectures.) 


APPENDIX. 


}8i 


XANTHIN  BODIES. 


NH-C=N 

/           1        >^^ 
Xanthin.    CO         C-NH 

CsH.NA.  \             1 

NH  -  CH 

NH-C=N. 

/         > 

Guanin.      C=NH  C-NH 
C,H,N,.0.      \           II 

NH-CH 

Heteroxanthin. 
CeHeN.O,. 

Adenin. 
CoH^N^.OH. 

N(CH3)-C=N. 

/                         >^^ 
Theobromin  .CO              C  -  N(  CH,) 

C^HsNA.     \                1 
NH    -    CH 

HypoxantMn. 
C6H,N4.0. 

Camin. 

CyHgN^O. 

N(CH3)-C=N. 

/         !    >^^ 

Theophyllin.  CO               C-NH 

O^H^N^O,.     \                 II 

N{CH3)-CH 

Paraxanthin. 
C^HgNA. 

N(CH3)-C  =  N. 

/        y^o 

CafFein.    CO                  C-N{CH,) 
CsHioN.O^    \                 1 

N(CH3)  -  CH 

{Rekmann.) 

RELATION  OF  UREA  TO  THE  CO^  DERIVATIVES 


AND  THE  CY-COMPOUNDS. 
0=c{gi  0=C{NH,  ._MNH, 


OH 
OH 
CSftrbonic  Acid. 


Carbamic  Acid.  Uraft«Carbaimd. 

/NH, 
C0a+2NH,=C0<( 

\O-NH4 
Carbamate  of  Ammonb 


382  APPENDIX. 

On  heatiiJg  to  130-140°  C.  :— 

/NH2  yNHa  yO-NH,  a, 

C0<  -H20  =  C0/  CO/  -aHaOrrCO/^ 

\O-NH4  \nH2  \O-NH4  NNH, 

Carbamate  of  Aiiirnonia.         Urea.  Ammonium  Carbonate.  Urea. 

By  heating  with  stroug  mineral  acids  or  alkalies  :  — 

/^^^         H  O  /O-NH4 

NNHa  \O-NH4 

Urea.  Carbonate  of  Ammonia. 

[Kmhenberg.\ 


CORRECTION    "FOR    TEMPERATURE     AND    PRESSURE 
IN  THE  HYPOBROMITE  METHOD  (LESSON  XIX.). 

Theoretically  i  gram  of  urea  evolves  372.7  cubic  centimetres  of  N,  but  in 
practice  it  is  found  from  urine  that  about  343  cc.  are  obtained.  Suppose  25  cc. 
of  N  passes  over  into  the  gas-collecting  tube,  and  that  the  temperature  of  thQ 
room  (0=  10°  C.  and  the  barometric  pressure  755  mm.  Hg,  what  is  the  volume 
at  standard  temperature  and  pressure  ? 

Let  V  be  the  required  volume  at  0°  C.  and  760  mm.  Hg  ;  v  be  the  volume 
read  oflf ;  P  =  pressure  of  760  mm.  Hg  ;  J9  the  barometric  pressure  of  the  room  ; 
T  the  absolute  temperature  = -273° ;  <  =  the  temperature  of  the  room  (in 
degrees  Centigrade +  273) ;  then 


_         25X755X273 

^-     760x283     -'3-9S«e. 


Next  to  urea,  uric  acid  is  the  most  important  substance  present  in  urine 
which  is  decomposed  by  hypobromite  of  sodium.  It  yields  47.7  per  cent,  of 
its  N.  But  as  the  quantity  of  uric  acid  present  in  urine  is  very  small,  for 
practical  purposes  it  may  be  neglected. 


CORRECTION  FOR  TEMPERATURE  AND  PRESSURE  OF 
THE  VOLUME  OF  A  GAS,  e.^.,  THE  GASES  OF  THE 
BLOOD. 

The  volume  of  a  gas  must  be  reduced  to  the  standard  pressure,  760  mm.  of 
Biercury,  and  standard  temperature,  0°  C,  according  to  the  formula : — 

76o(H-aO 


APPENDIX.  -  383 

V— the  required  volume  at  standard  temperature,  0°  C,  and  760  mm.  Hg. 

V^  =  the  volume  at  the  observed  temperature  and  pressure. 
h  =  the  observed  pressure. 

a  =  the  coefficient  of  expansion,  which  is  a  constant  (,003665). 
t  =  the  observed  temperature. 

The  formula  is  obtained  as  follows  :  — 

With  reference  to  the  correction  of  the  given  volume  for  temperaiwn  •• 

l+at:  I  ::  VI  :V 
V^ 


and  for  pressure  : 


■vat 


l-Vat 


hi  760 


760  {i+at) 

Example. — Suppose  the  volume  of  gas  to  be  corrected  for  temperature  and 
pressure,  i.e.,  V^  =  30  cc,  the  observed  barometric  pressure,  i.e.,  ^=-740  mm., 
and  the  temperature  of  the  room,  i.e.,  t^-is"  C,  then  the  required  volume 
will  be : 

_,  30  X  740  22200  - 

760  ( I +.003665  X  15)     801.78100       '* 

».«.,  30  CC.  of  a  gas  at  740  mm.  pressure  and  15°  C.  are  reduced  to  27.6  cc.  at 
standard  pressure  and  temperature  (760  mm.  and  0°  C). 


SOLUBILITIES  IN  WATER  AT  15*  to  i8'  C. 

Ammonium  chloride, 36  per  100. 

Sodium  chloride, 3^   >>     f» 

Ammonium  sulphate, 5°  f»     i» 

Magnesium  sulphate 125  „     „ 


IV. 
RECORDING  APPARATUS. 

There  are  many  forms  of  recording  apparatus  in  use,  and  some  of  them  are 
described  in  the  text  (Lesson  XXXIV.).  When  a  number  of  students  have  to 
be  taught  to  record  graphically  the  results  obtained  in  an  experiment,  then 


384  APPENDIX. 

drums  moved  by  some  kind  of  motor  are  essential.  Drums  moved  by  clock- 
work, however  convenient  for  individual  work,  are  not  suitable  for  students' 
purposes.  Hence  various  devices  are  used  so  that  many  men  are  enabled  to 
work  at  separate  drums  at  the  same  time. 

Motor, — One  has  first  to  consider  what  form  of  motor  one  shoulQ  use  co 
drive  the  drums.  Some  use  a  small  gas-engine,  others  use  a  water-motor,  as, 
for  example,  the  Swiss  form  of  motor  made  by  Schmidt,  or  the  Thirlmere  form, 
while  others  prefer  an  electric  motor  where  electricity  is  available.  Such  an 
electric  motor  is  made  by  Siemens  and  Halske,  Berlin,  but  the  initial  cost  of 
this  apparatus  is  considerable. 

Transmission  of  Motion.  — Next  arises  the  question  as  to  how  the  motion  is 
to  be  transmitted  to  the  drum.  This  is  don^  in  various  ways.  In  the 
Cambridge  system,  which  is  adopted  foi  some  of  the  drums  in  the  Physio- 
logical D'^-partment  of  Owens  College,  the  motion  is  transmitted  from  the 
motor — gas-engine  or  Thirlmere  water-motor  placed  in  the  basement — by  means 
of  an  endless  quick-running  cord.  This  method  is  extremely  convenient,  and 
the  drums  are  so  made  that  they  can  be  readily  arrested,  and  can  also  be 
made  to  move  at  diflferent  speeds. 

Some  use  shafting  fixed  on  a  support  on  the  wall  or  ceiling  or  on  a  table. 
To  the  shaft  are  fixed  coned  pulleys,  i.e.,  wheels  of  different  diameters,  whereby 
a  good  range  of  speeds  cac  be  obtained. 

Recording  Drum. — Next  comes  the  form  of  drum  to  be  used.  In  the 
Cambridge  arrangement  the  drum  can  be  raised  or  lowered  on  a  vertical  axis 
by  means  of  a  clutch,  while  the  drum  itself  can  be  set  in  motion  or  arrested  by 
means  of  a  handle  on  the  driving  pulley.  The  rate  of  movement  can  also  be 
changed  as  desired. 

Prof.  Schafer  has  also  designed  a  form  of  drum  which  is  moved  by  a  short 
cord  passing  over  coned  pulleys  fixed  to  a  long  rod  placed  on  bearings  fixed  to 
a  tible  and  moved  by  a  water-motor.  It  is  made  by  Backhouse,  Physiological 
Department,  University  College,  London. 

The  Oxford  pattern  is  somewhat  different  from  this,  and  is  made  by  Butler, 
Physiological  Department,  Oxford. 

In  Hering's  large  kymographion  there  is  a  long  sheet  of  paper  (2  metres) 
stretched  over  an  iron  framework,  which  is  moved  by  clockwork  driven  by  a 
weight.  In  University  College,  London,  to  this  framework  a  small  cogwheel 
is  adapted  whereby  this  arrangement  can  easily  be  driven  by  an  ordinary 
motor.  It  is  specially  useful  for  research  work  where  a  moderate  or  slow  speed 
of  the  recording  surface  is  required. 

In  the  "physiological  recording  drum"  (fig.  288),  as  made  for  Dr 
Sherrington,  the  cylinder  is  6  inches  by  6  inches,  and  is  so  arranged  that  it 
can  be  used  in  a  vertical  or  horizontal  position,  and  has  a  lever  by  which  it 
can  be  instantly  started  or  stopped  at  any  portion  of  a  revolution.  The  cone 
pulley  gives  a  good  range  of  speeds.  The  brass  cylinder  is  turned  perfectly 
true  in  a  self-acting  lathe,  and  has  about  5  inches  vertical  adjustment.  It  is 
easily  removed  for  the  purpose  of  blacking,  and  can  be  run  by  any  light  motor 
or  clockwork,  as  desired.     The  whole  is  mounted  upon  a  substantial  cast-iron 


APPENDIX. 


38i 


base,  so  as  to  stand  firm  without  clamping  down.     It  is  made  by  C.  F.  Palmer, 

5  Kellett  Road,  Brixton,  S.W. 

It  costs  as  above ;^5  ^2    6 

Or  with  levelling  screws  (vertical  and  horizontal)     .         .        ,     6    O    o 
Extra  for  automatic  break-key  (as  shown  in  position)  «     O    8    6 


fn.  288.— Sherrington's  Dmm. 


Professor  de  B.  Birch's  System  of  Recording  Apparatus,— The  following 
description  applies  to  a  system  of  recording  apparatus  devised  for  the  Experi- 
mental Laboratory  in  the  New  Medical  School  buildings  of  the  Yorkshire 
College.  The  motive  power,  a  small  Chicagos  top,  is  geared  for  reduction  of 
speed  to  a  54-inch  bicycle  wheel,  and  this  again  by  a  cord  to  a  piece  of  shafting, 
19  feet  long,  running  on  ball  bearings  and  supported  by  brackets  fixed  to  the 
wall  of  the  Laboratory.  The  shafting  carries  step  cones  (I,  fig.  289),  to  these  the 
drums  are  geared  by  cords  which  run  over  guide  pulleys  suspended  from  the 
ceiling  in  convenient  positions.  The  tension  on  these  cords  is  kept  constant 
by  counter  weights  (L),  which  allow  the  former  the  play  required  in  shifting 
from  one  speed  to  another  on  the  cones  when  changing  the  rate  of  revolution 

2  B 


386 


APPENDIX. 


y^'^a 


APPENDIX.  387 

of  the  drums.  An  inverted  cone  outside  the  pulley  ^D)  reduces  the  chance 
of  the  cord  being  liberated  from  (D)  during  the  latter  operation. 

The  drums  can  be  run  in  practically  any  position  on  their  table,  and  they 
can  be  removed  from  the  latter  without  trouble,  the  gearing  cords  when  not  in 
use  being  attached  to  hooks  on  the  wall  close  to  the  shafting.  The  tables  are 
thus  left  completely  free  for  other  purposes.  The  drums  are  provided  with  a 
starting  and  stopping  contrivance  (B)  which  is  independent  of  the  gearing 
cord.  The  driving  spindle,  which  carries  the  cone  (D)  and  pulley  (E),  runs 
in  ball  bearings  in  a  rocking  carrier  which  is  tilted  by  the  lever  (B)  either 
into  contact  with  or  free  of  (F),  a  disc  attached  on  the  cylinder  axle.  This 
axle  is  also  on  ball  bearings.  The  drum  can  be  readily  adjusted  for  height 
or  removed  for  covering  and  smoking  without  stopping  the  driving  spindle. 

The  running  parts  are  throughout  the  system  either  on  centres  or  on  ball 
bearings.  The  resultant  diminution  of  friction  is  so  considerable  that  the 
small  motor  already  mentioned  turns  eight  to  twelve  cylinders  easily  with  a 
25 -pound  water  pressure. 

The  disc  (F)  has  holes  bored  into  its  edge  into  which  a  pin  or  pins  can  be 
fixed  for  making  contact  with  (H)  when  automatic  stimulation  is  required  at 
a  definite  epoch  in  the  revolution  of  the  cylinder. 

The  stand  (M)-^  lends  itself  to  most  experiments  on  frog  muscle,  nerve,  and 
heart.  The  bracket  (P),  adjustable  on  the  pillar  (N),  will  carry  any  ordinary 
form  of  muscle-chamber,  &c. ,  with  slight  adaptation.  For  the  support  of  a 
time-marker  the  "stirrup"  (Q)  is  provided.  This  turned  behind  the 
muscle-chamber  will  hold  a  rod  u])on  which  the  muscle-lever  can  be  rested  in 
an  after-load  experiment,  or  to  which  a  spring  can  be  attached  for  the  muscle 
to  pull  upon  in  taking  an  isometric  myogram.  The  same  can  be  accomplished 
with  the  stirrup  in  the  front  position  by  using  a  second  clamp  and  bent  metal 
rod. 

The  points  of  the  writing-levers,  after  being  adjusted  by  hand,  can  be  finely 
adjusted  or  lifted  off  the  paper  by  means  of  the  adjusting  screw  and  lever 
(0).     Stability  is  conferred  by  the  weight  of  metal  in  the  stand  (Birch). 


MICRO-CHEMICAL  DETECTION  OF  GLYCOGEN,  IRON 
AND  PHOSPHORUS  IN  VARIOUS  CELLS. 

Glycogen  in  Liver  Cells, — The  essential  part  of  this  process  is  that,  as 
glycogen  is  soluble  in  water,  the  liver  or  other  tissue  supposed  to  contain  the 
glycogen  must  not  be  placed  in  icater.  Feed  a  rabbit  on  carrots,  and  5-6 
hours  afterwards  kill  it  ;  cut  part  of  the  liver  into  small  pieces  and  harden 
them  in  absolute  alcohol.     Cut  hand  sections,  moistening  the   razor  with 

1  Since  this  stand  was  devised  about  three  years  ago,  Dr  Birch  has  become  acquainted 
with  the  fact  that  Runne  of  Basle  makes  a  stand  of  somewhat  similar  construction  which 
he  calls  the  Basler  stativ. 


388  APPENDIX. 

alcohol,  or  embed  and  cut  in  paraffin.  Get  rid  of  the  paraffin  by  means  of 
turpentine,  and  treat  both  the  paraffin  and  alcohol  sections  with  chloroform 
in  which  iodine  is  dissolveil,  and  mount  in  chloroform  balsam  containing  some 
iodine.  The  brown  stain  in  the  liver  cells  indicates  glycogen,  which  is 
deposited  chiefly  in  the  cells  around  the  hepatic  vein  [DeUpine). 

Iron. — (a.)  The  tissue — liver  ot  young  animal,  or  spleen— must  be  hardened 
in  alcohol.  The  sections  are  transferred  to  a  freshly -prepared  solution  of 
potassium  ferrocyanide  acidulated  with  hydrochloric  acid.  The  granules  of 
iron  become  blue  {Tizzoni). 

{b.)  Harden  the  liver  in  65  p.c.  alcohol,  then  in  90  p.c.  alcohol  to  which  a 
few  drops  of  sulphuretted  hydrogen  are  added.  After  twenty-four  hours  the 
iron  granules  become  green  {ZahsJci). 

Phosphorus. — Place  sections  of  the  fresh  organ  for  half  an  hour  in  a  strong 
solution  of  ammonium  molybdate,  and  then  transfer  them  to  a  20  p.c. 
solution  of  pyrogallic  acid  dissolved  in  ether.  After  a  few  minutes  pass 
them  through  spirit  and  clove  oil,  and  mount  in  Canada  balsam.  A  com- 
pound containing  phosphorus  is  stained  yellow  or  brown,  and  such  compounds 
are  usually  found  in  the  nuclei.  It  is  stated  that  by  this  method  nucleo- 
albumin  may  be  distinguished  from  mucin  {LUienfeld  and  MorUi). 


KJELDAHL'S  METHOD  OF  ESTIMATING  NITROGEN. 

1.  Destruction  of  Organic  Matter. — Place  in  a  boiling  flask  ot  ICX5  cc. 
capacity  o.  i-i  gramme  of  the  powdered  dry  substance.  To  destroy  the  organic 
matter  add  10-20  cc.  of  the  following  mixture :  200  cc.  pure  oil  of  vitriol,  50 
cc.  Nordhausen  oil  of  vitriol,  phosphoric  acid  in  sticks,  2  grammes,  all  free 
from  ammonia.  Heat  on  a  wire  gauze  with  a  Bunsen-burner,  but  keep  the 
temperature  below  boiling.  To  hasten  the  destruction  a  little  potassium 
permanganate  may  be  added.  Heat  for  1-2  hours  until  the  fluid  becomes 
clear  and  greenish. 

2.  Neutralisation.  —  Cool  the  flask,  add  a  little  water,  and  wash  the  contents, 
with  as  little  water  as  possible,  into  a  large  flask  of  700  cc.  capacity. 
Neutralise  with  pure  caustic  soda  or  potash  (S.G.  1.13).  Add  a  little 
metallic  zinc  to  prevent  bumping  during  the  subsequent  distillation. 

3.  Distillation. — Rapidly  close  the  flask  with  a  perforated  caoutchouc  stopper 
through  which  passes  a  tube  with  two  i  inch  bulbs  blown  upon  it.  The  bulbs  are 
to  collect  and  prevent  the  passage  of  soda  spray.  The  tube  above  the  bulbs 
passes  through  a  condenser,  and  the  delivery  tube  end  of  the  condenser  tube 
passes  into  a  flask  containing  a  measured  excess  of  standard  acid  (HCl). 
Distil  the  mixture  about  an  hour  in  the  flask,  and  the  ammonia  passes  over 
into  the  acid. 


APPENDIX.  389 

4.  Titration. — Determine  the  amount  of  acidity  in  the  distillate  by  titration 
with  a  standard  solution  of  caustic  soda  or  potash,  methyl  orange  being  used 
as  an  indicator  of  the  end  of  the  reaction.  Methyl  orange  gives  a  pink  with  an 
acid,  and  yellow  with  an  alkali. 

The  apparatus  used  in  the  Physiological  Laboratory  of  Owens  College  is 
that  made  by  Messrs  Baird  and  Tatlock  (see  their  catalogue),  and  is  so 
arranged  that  several  estimations  can  be  made  simultaneously.  Other  modi- 
fications are  in  use. 

Example. — Suppose  o.  15  gramme  of  the  N-substance  has  been  treated  with 
acid,  neutralised,  and  the  ammonia  distilled  over  and  received  by  100  cc.  of  a 
decinormal  solution  of  HCl  ( =  10  cc.  normal  acid).  The  distillate  is  then  treated 
with  decinormal  caustic  soda,  and  suppose  it  is  found  that  the  neutral  point 
is  reached  when  60  cc,  of  the  decinormal  soda  has  been  added.  The  remaining 
40  cc.  must  therefore  have  been  neutralised  by  the  ammonia  obtained  from  the 
nitrogenous  substance  investigated.  This  40  cc.  of  decinormal  acid  =  4  cc.  of 
normal  acid  =  4cc.  ofnormalammonia  =  4x  0.017  =  0.068  gramme  of  ammonia  : 
o.  15  gramme  of  the  substance,  therefore,  yields  0.068  gramme  of  ammonia,  and 
this  amount  contains  0.056  gramme  of  nitrogen  ;  100  grammes  of  the  substance 

investigated  will  therefore  contain  ^^^-7°^°^    =37*3  grammes  of  nitrogen.— 

(From  Sutton's  VolumetrU  Analysis  by  Warington.) 


MEASURES  OF  LENGTH. 

Metric  System. 

The  standard  is  the  metre  ;  for  multiples  of  the  metre  prefixes  deca-  liecto< 
and  kilo-  are  used  ;  for  subdivisions  thereof,  milli-  centi-  and  deci-  are 
used  just  as  in  the  case  of  the  gramme  in  the  table  below. 

I  millimetre  =0.001  metre  =  0.03937  inch. 

I  centimetre  =  0.01        ,,     —  0.3937        ,, 

I  decimetre  -o.io       „     —  3.93707  inches. 

I  metre  -39-37079      *t 


English  System. 

I  inch  —  25.4  millimetret. 

I  foot  —  1 2  inches  -  304. 8  „ 


390  APPENDIX. 

MEASURES  OF  CAPACITY. 

Metric  System. 

A  litre  is  the  standard,  and  is  equal  to  lOOO  cubic  centimetres  (lOOO  cc.)i 
each  cubic  centimetre  is  the  volume  of  i  gramme  of  distilled  water  at  4°  C. 

I  cubic  centimetre  (i  cc.)=  16.931  minims, 

I  litre=  1000  cc.  =  i  pint  15  oz.  2  drs.  11  min.  (35.2154  oz.) 

English  System. 

I  minim  —     0.059    cubic  centimetre. 

1  fluid  drachm  =  60  minims  =-     3-549    cubic  centimetres. 

I  fluid  ounce    =  8  fluid  drachms  •=  28.398         ,,  „ 

I  pint  —20  fluid  ounces     =567936         ,,  ,, 

I  gallon  —  8  pints  =     4.54837  litres. 


WEIGHTS. 

MetrU  System. 

I  milligramme  =- 

0.00 1  gram.  — 

I  centigramme  = 

O.OI         ,,       — 

I  decigramme  = 

0.1          ,,      — 

I  gramme          = 

I             »      - 

I  decagramme  = 

10        grams.  =-      i 

I  hectogramme  = 

100            „       =    15 

I  kilogramme    = 

1000            „      =154 

0.015432  grain. 
0.154323      n 
1.543235      >f 
15-43235    grains. 
1543235 
543-235  >* 

)  II 

=  2  lb.  3  oz.  1 19.8   ,, 

[For  practical  purposes  the  kilogramme  or  kilo  is  taken  at  2.2  lbs.] 

English  System. 

I  grain  —     0.0648  gramme. 

I  ounce- 437. 5         grains  =»  28.3595  grammes. 

115.-1602.-7000         „  -435-5925  !• 


APPENDIX.  391 


THERMOMETRIC  SCALES. 

Fahrenheit  scale,  freezing  point  of  water  32°,  boiling  point  212* 
Reaumur        ,,  ,,  ,,  „       0°      „  „        So* 

Centigrade     ,,  ,,  „  »>       0°      »  „       100° 

To  convert  degrees  F.  into  degrees  C.  subtract  32  and  multiply  by  f  or 
C  =  (F-32)5.     To  convert  C°  into  T  the  formula  is  F-|  O  +  32. 


SOME  OF  THE  INSTRUMENT-MAKERS  WHO  SUPPLY 
PHYSIOLOGICAL  APPARATUS. 

Backhouse,  University  College,  London. 
Butler,  Physiological  Laboratory,  Oxford, 
Cambridge  Scientific  Instrument  Co. 
Hume,  Lothian  Street,  Edinburgh. 
Kershaw,  Cankerwell  Lane,  Leeds. 
Meyer  (J.  F. ),  Seilergraben  7,  Zurich. 
Palmer,  5  Kellett  Road,  Brixton,  Londom 
Petzold,  Bayerische  Strasse,  Leipzig, 
Rothe,  Wenzelbad,  Prague. 
Siedentopf,  Wiirzburg. 
Runne,  Basel  and  Heidelberg. 
Verdin,  Rue  Linne  7,  Parii. 
Zimmermauu,  Leipzig. 


INDEX 


Aberration— Chromatic,  330. 

,,  spherical,  330. 

Absorption-bands,  47. 
Accommodation,  331. 

„  line  of,  335. 

Aceto-acetic  acid,  146. 
Aceton,  146. 

Achroo-dextrin,  18,  22,  69. 
Acid-albumin,  8,  73. 
Acid-hsematin,  50. 
Acidulated  brine,  138. 
Acme  sacchar-ureameter,  145. 
Action-current  of  muscle,  237. 

,,  ner\>e,  238. 

Acuity  of  vision,  339. 
Adamkiewicz,  reaction  of,  3. 
iEsthesiometer,  367. 
After-images,  359. 
After-load,  200. 
Air  expired,  311. 

,,  analysis  of,  813. 

Albumenoids,  13. 
Albumin,  1. 

„  coagulation   temperature 

of,  4. 

derived,  7. 

^gg,  14. 

general  reactions,  2. 

native,  4. 

nitrogen  in,  3. 

serum,  5. 

soluble,  4. 

sulphur  in,  3. 

vefjetable,  98. 
Albumin — Estimation  of,  139. 

in  urine,  136. 

tests  for,  137. 
Albuminates,  73. 
Albuminimeter,  139. 
All'uminuria,  136. 
Albumoses,  8,  73,  78. 


Alkali -albumin,  7. 
Alkali-haematin,  51. 
,,       reduced,  51. 
Alkaline  phosphates,  112. 
Amalgamation  of  zinc,  158. 

,,  mixture,  15S. 

Amidulin,  22. 
Ammonium  carbonate,  109,  382. 

„  urate,  151. 

Ampke,  160. 
Amyl  nitrite,  294. 
Amyloid  substance,  11, 
Amylopsin,  80. 
Amy  loses,  16. 
Anaglyph,  363. 
Analysis  of  a  fluid,  32. 
„  solid,  156, 

Animal  starch,  19. 
Anode,  157. 
Apex-preparation,  282. 
Apnoea,  310. 

Apparent  movements,  350. 
Aromatic  compounds,  378. 
Arterial  pressure,  301. 
Artificial  eye,  350,  365. 

,,        gastric  juice,  71. 

,,         pancreatic  juice,  79. 
Aristotle's  experiment,  368. 
Astigmatism,  335. 
Atropin  on  heart,  277. 
Auto-laryngoscopy,  316. 
Automatic  break  excitation,  201. 
Auxocardia,  291. 

Barfoed's  solution,  2. 
Baryta  mixture,  124. 
Bayliss'  writing-point,  270. 
Benham's  top,  362. 
Benzoic  acid,  131. 
Benzo-purpurin,  76. 
Berf^mann's  experiment,  340, 
Bernard's  method  for  curare,  193. 


INDEX. 


393 


Bernstein's  method  for  heart,  261. 
Bezold's  experiment,  330. 
Bichromate  cell,  159. 
Biedermann's  modification,  243. 
Bile,  87. 

,,    acids,  87. 

,,    actions  of,  89. 

,,    cholesterin  in,  89, 

,,    crystallised,  87. 

„    Gmelin's  test,  88,  141. 

,,    in  urine,  141. 

„    Petteukofer's  test,  88,  141. 

,,    pigments,  88. 

,,    salts,  87. 
Bile-acids  in  urine,  111. 
Bile-pigments  in  urine,  141. 
Billn,  87. 
Bilirubin,  88. 
Biliverdin,  88. 
Binocular  contrast,  359. 

,,         vision,  345. 
Biuret  reaction,  9,  119. 
Bismuth  test,  21, 
Black-band  experiments,  342. 
Black's  experiment,  311. 
Blind  spot,  337. 
Blix's  myograph,  217. 
Blood,  33. 

„       acids  on,  55. 

,,       action  of  saline  solution,  34. 

„       Buchanan's  experiments,  39. 

,,       clot,  35. 

,,      coagulation  of,  35. 

„       corpuscles,  43. 

,,       defibrinated,  37. 

,,      grape-sugar  in,  42. 

,,       laky,  33. 

„       mammalian,  35. 

,,       nitrites  on,  53. 

„       plasma,  35. 

,,       reaction,  33. 

,,       red  corpuscles  of,  34. 

,,       sernm  of,  35,  37. 

,,       sodium  fluoride  on,  54. 

,,       specific  gravity  of,  34. 

,,       spectroscopy  of,  46. 

,,       stains,  59. 

,,       transparent,  33. 
Blood  in  urine,  140. 
Blood-corpuscles,  43. 

,,  numeration  of,  43. 

Blood-gases,  312. 
Blood -pressure,  300,  306. 

„  tracings,  304. 

Bone,  31. 
Bottger*s  test,  21,  142. 


Bowditch's  rotating  coil,  167. 

Bread,  99. 

Break  extra-current,  173. 

Break-shock,  171. 

Brine-test,  138. 

British  gum,  18. 

Briicke's  method  for  glycogen,  91. 

Brush  electrodes,  237. 

Buchanan's  experiments,  39. 

Bufty  coat,  35. 

Burette,  116. 

Calcium  phosphate,  112. 
Calculi,  urinary,  149. 
Cane-sugar,  24. 

,,  estimation  of,  25. 

,,  inversion  of,  24. 

Cannula,  305. 

Capillaries,  pressure  in,  300. 
Capillary  electrometer,  233. 
Carbohydrates,  15,  376. 

,,  classification  of,  16 

,,  general  characters,  15. 

,,  rotatory  power,  28. 

Carbolo-chloride  of  iron  test,  77. 
Carbonic-oxide  haemoglobin,  47. 

,,  spectrum  of,  57. 

Cardiac  delay,  272. 
Cardiogra])h,  287. 
Casein,  11. 
Caseinogen,  8,  95. 
Cathode,  157. 

,,         as  stimulus,  249. 
Cellulose,  19. 

Centrifugal  machine,  43,  147. 
Charpentier's  experiments,  342, 
Chemical  stimulation,  182. 
Chloral,  321. 
Cholesterin,  89,  90. 
Cholic  acid,  88. 
Chondrin,  14. 
Chondrigen,  14. 
Chordogram,  206. 
Choroidal  illumination,  359. 
Christison's  formula,  106. 
Chromatic  aberration,  330. 
Chromo-cytometer,  62. 
Chronograph,  211. 
Ciliary  motion,  177. 
Circulation,  scheme  of,  297. 

,,  microscopic   examination 

of,  300. 
Circumpolarisation,  25. 
Clerk-Maxwell's  experiment,  340. 
Coagulated  proteids,  10. 
Coagulation  of  blood  35. 


394 


INDEX. 


Coagulation,  action  of  neutral  salts, 36. 
„  ,,     of  cold,  35,  40. 

,,  experiments,  39. 

,,  oxalates,  36. 

Cold — Effects  on  blood,  35. 
„  ,,  heart,  264. 

„  „  muscle,  213. 

,,  ,,  nerve,  257. 

Cold  spots,  3»69. 
Collagen,  13. 
Colloid,  19. 

Colorimetric  method,  65. 
Colour-blindness,  353. 

,,      sensations,  352. 
Coloured  fringes,  330. 

,,        shadows,  358. 
Conibined  sulphuric  acid,  112, 
Commutator,  165. 
Conduction  in  nerve,  247,  256. 
Congo-red,  76. 
Constant  current,  160. 

,,  ,,       action  of,  254. 

„  ,,  ,,     on  heart, 278. 

Contact  key,  162. 

„       sense  of,  370. 
Contraction — maximal,  199. 
,,  minimal,  198. 

,,  paradoxical,  241. 

,,  secondary,  241. 

„  without  metals,  239. 

Contrast,  354. 

„         binocular,  359. 
Crank-myograph,  200. 
Crystallin,  7. 
Curare,  190,  193. 
Curdling  of  milk,  96. 
Current,  demarcation,  234,  237. 
„        of  heart,  242. 
„        of  injury,  234. 
Cystin,  151. 

Darnell's  cell,  157. 
Darby's  fluid  meat,  9. 
D'Arsonval's  N.  P.  electrodes,  237. 
Defibrinated  blood,  37. 
Deglutition  apnoea,  310. 
Demarcation  currents,  234. 
Deposits  in  urine — organised,  147. 

,,  unorganised,  147. 

Depressor  nerve,  302. 
Derived  albumins,  7. 
Despretz's  signal,  210. 
Detector,  159. 
Deutero-albumose,  78. 
Dextrin,  18. 

„         preparation  of,  19. 


Dextrin,  varieties  of,  22, 
Dextrose,  20. 

,,         reducing  power  of,  70, 
,,         rotatory  power  of,  26, 
Diabetes,  143. 
Dialyser,  78. 
Diffusion,  329. 
Digestion — Biliary,  87. 
,1  gastric,  71. 

,,  pancreatic,  79. 

,,  salivary,  67. 

Diplopia  monophthalmica,  336, 
Direct  stimulation,  188. 

„      vision,  339. 
Direction,  judgment  of,  848. 
Disaccharides,  16. 
Distance,  judgment  of,  348. 
Donne's  test,  148. 
Double  conduction  in  nerve,  253. 
Du  Bois  electrodes,  169. 
,,        induction  coil,  166. 
„        key,  160. 
,,        rheochord,  249. 
Dudgeon's  sphygmogiaph,  294. 
Du})re's  apparatus,  121. 
Duration  of  impressions,  342. 
Dynamometers,  189. 

Ear,  371. 

Earthy  phosphates,  112, 
Egg-albumin,  4. 
Elasticity  of  artery,  218, 
„  lungs,  309. 

,,  muscle,  216, 

Elastin,  14. 

Electrical  keys — Brodie's,  175. 
„  Contact,  162. 

„  Du  Bois,  160. 

„  mercury,  162. 

„  Morse,  162. 

plug,  163. 
„  spring,  162. 

trigger.  162. 
Electrical  constant  current,  184. 
„         repeated  shocks,  184. 
,,         single  shocks,  183. 
,,         stimulation,  183. 
,,         stimuli,  181. 
Electrodes,  168. 

,,  d' Arson val's,  237. 

„  brush,  237. 

„  Du  Bois,  169. 

,,  for  nerve,  304. 

,,  non-polarisable,  233. 

,,  polarisation  of,  169, 

Electrometer,  capillary,  238. 


INDEX. 


395 


Electro-motive  phenomena  of  muscle, 
235. 

Electro-motive  phenomena  of  heart, 
238,  242. 

Electro-motive  phenomena  of  electro- 
tonic  variation,  248. 

Electro-tonic  variation  of  excitability, 
243. 

„  „         electro-motivity, 

248. 

Electrotonus,  243. 

Ellis'  air  piston  recorder,  296. 

Emulsion,  30,  83. 

Endocardial  pressure,  281. 

Engelmann's  experiment,  254. 

Entoptical  vision,  341. 

Enzymes,  68,  75. 

Erdinann's  float,  116. 

Ergograph,  230. 

Erythro-dextrin,  18,  22,  69. 

Esbach's  albuminimeter,  139. 

Ewald's  coil,  167. 

Examination  of  a  fluid   for  proteids 
and  carbohydrates,  32,  154. 

Examination  of  a  solid,  156. 

Excitability,  muscular,  190. 

„  V.  conductivity,  256. 

,,  of  nerve,  254,  266. 

Exhaustion  in  nerve  and  muscle,  225. 

Experimentum  mirabile,  327. 

Expired  air,  311. 

Extensibility  of  muscle,  216. 

Extensors,  excitability  of,  256. 

Extra-current,  173. 

Far  point,  333. 
Faradic  electricity,  166. 
Faradisation,  172. 
Fatigue  of  muscle,  223. 

„  nerve,  225. 

Fats,  neutral,  29. 
Fehling's  solution,  142, 
Ferments — Aniylojjsirt,  80, 

,,  fibrin,  40. 

,,  milk  curdling,  84,  96. 

„  pancreatic,  80. 

„  pepsin,  72. 

„  pialyn,  84. 

„  ptyalin,  68. 

,,  rennet,  75. 

,,  steapsiri,  84. 

,,  trypsin,  81. 

,,  in  urine,  136. 

Fibrin,  10,  37. 
Fibrin-ferment,  40. 
Fibrinogen,  7,  36,  89. 


Field  of  vision,  344. 
Flexors,  excitability  of,  256. 
Flour,  98. 
Fovea  centralis,  339. 

,,  shadows  on,  341. 

Fractional  heat-coagulation,  11, 
Furfarol,  88. 

Gad's  emulsion  experiment,  30. 
Gall  stones,  89. 
Galvanic  electricity,  157. 
Galvani's  experiment,  239. 
Galvanometer,  251. 
Galvanoscope,  159. 
Garrod's  test,  129. 
Gas-sphyfjmoscope,  296. 
Gases  in  blood,  312. 
Gaskell's  clamp,  267. 

,,         heart  lever,  266. 
Gastric  action  on  milk,  75. 

„       contents,  examination  of,  79. 

,,       digestion,  72. 

„      juice,  72. 

,,       peptones,  74. 

,,       products  of,  73. 
Gelatin,  13. 

Gerrard's  urea  apparatus,  126. 
Globin,  7. 
Globulins,  6. 
Globulinuria,  138. 
Glucose,  20. 

,,        in  blood,  42. 
„        to  prepare,  22. 
,,       rotatory  power  of,  26. 
Glucoses,  16. 
Gluten,  11,  98. 
Glycerin,  29. 
Glycin,  104. 
Glyco-cholic  acid,  87. 
Glycocol,  104. 
Glycogen,  19,  91. 

,,         preparation  of,  91. 
„         tests  for,  93,  387. 
Glycosamin,  103. 
Glycosuria,  141. 
Gmelin's  test,  88. 
Goltz's  tapping  experiment,  287. 
Gotch'a    arrangement    for    excised 

heart,  269. 
Gotch's  localised  cold  nerve,  258. 
Gracilis,  experiment  on,  253. 
Grape-sugar,  20,  42. 
Graphic  method,  194. 
Grove's  cell,  158. 
Griiiihagen's  experiment,  256. 
Guaiacum  test,  140. 


396 


INDEX. 


Guanin,  104. 
Gymneraa  sylvestre,  371. 

Haematin,  52. 

,,  prej^>aration  of,  58. 

Hsematinoiueter,  49. 
Htematoporphyrin,  63. 
Haeraatoscojie,  49. 
Haematuria,  140. 
Hreniin,  59. 
Haeniochromogen,  51, 
Haemocytometer,  43. 
Haemoglobin,  34. 

„  ash  of,  43. 

„  carbonic  oxide,  49,  67. 

„  crystals  of,  45. 

„  estimation  of,  59. 

,f  nitrites  on,  53. 

„  non-diffusibility,  34. 

„  oxy-,  47. 

„  ozone  test,  46. 

„  preparation  of,  45,  65. 

,,  reduced,  48,  56. 

,,  spectrum  of,  47,  55. 

Haemoglobinometer,  59. 
Haemoglobinuria,  140. 
Haemometer,  60. 
Hand-electrodes,  168. 
Haploscope,  360. 
Haser-Trapp's  coeflficient,  106. 
Haycraft's  method  for  S.  G.  of  blood, 
34. 
,,  uric  acid,  136- 

Hearing,  371. 

Heart — Action  of  drugs  on,  277. 
„        apex,  282. 
„        atropin  on,  277. 
,,         casts  of,  285. 
,,         clamp,  267. 
,,         cold  on,  261. 
,,         constant  current  on,  278. 
,,         current  of  frog,  242. 
,,         endocardial  pressure,  281. 
„         excised,  260,  269. 
,,         frog's,  259. 
,,         graphic  record  of,  262. 
„         heat  on,  261. 
„         inhibition  of,  271. 
„         inhibitory  centre,  271. 
,,        latent  period,  272. 
„        lever,  263. 
„     -    mammal's,  286. 
,,         motor  centres,  272. 
„        movements  of,  262. 
„        muscarine,  277. 
„        nervous  system  on,  279. 


Heart  —effect  of  temperature  on,  260. 
264,  267. 

„        nicotin  on,  277. 

„        ox,  286. 

,,         perfusion,  279. 

„         pilocarpin  on,  277. 

„        record  of,  262. 

„        reflex  inhibition,  271,  287. 

,,         section  of,  261. 

,,         sounds  of,  286. 

„         staircase  of,  271,  278. 

,,         Stannius's  experiment,  270. 

,,        suspension  methods,  266. 

„         swallowing  on,  287. 

,,         sympathetic  on,  275. 

,,         tonometer,  282. 

,,         tortoise's,  265. 

,,         vagus  on,  273,  306. 

,,         valves  of,  284. 
Heat— Effect  on  cilia,  177. 

,,  ,,         heart,  264. 

,,  ,,         muscle,  214. 

,,  ,,         nerve,  255, 

Heat-rigor  of  muscle,  206, 
Heller's  test,  137. 

,,       blood  test,  140. 
Helmholtz's  modification,  174. 
Hemialbumose,  8,  78. 
Hempel's  method,  314. 
Hering's  apparatus  for  contrast,  357. 
Hetero-albumose,  78. 
Heywood's  experiment,  313. 
Hippuric  acid^  131. 
Holmgren's  worsteds,  354. 
Hot  spots,  369. 

Hiifner's  urea  apparatus,  120,  125. 
Hydrocele  fluid,  39. 
Hydrostatic  test,  310, 
Hypobromite  method,  120. 
Hypobromite  of  sodium,  121. 

niuminated  ox  heart,  286. 
Illusions  connected  with  skin,  370. 
Image,  formation  of,  329. 
Impressions,  duration  of,  342. 
Independent    muscular    excitability, 

190. 
Indican,  134. 
Indifferent  fluid,  179. 
Indigo-forming  substance,  134. 
Indirect  stimulation,  188. 

„        vision,  339. 
Indol,  83,  85. 
Induced  electricity,  166. 
Induction  coil,  166. 

„        Ewald'a  form,  167. 


INDBX. 


397 


Induction,  new  form  of,  166. 

,,         graduated  form  of,  167. 

,,         shocks,  effects  of,  171. 
Inflammation,  300. 
Inhibition  of  rabbit's  heart,  287. 
Inhibitory  heart  arrest,  271,  287. 
Interrupted  current,  172. 
Intra-ocular  pressure,  367. 
Intra-pleural  pressure,  312. 
Intra- thoracic  pressure,  311. 
Inverted  image,  329. 
Invert-sugar,  25. 
Iodine  solution,  18. 
Iris,  movements,  326. 
Iron,  test  for,  388. 
Irradiation,  346. 
Isometric  contraction,  203. 
Isotonic  „  203. 

Jaffe's  test,  133. 
Judgment  of  direction,  348. 

,,         of  distance,  348. 

,,         of  size,  348. 

Keratin,  14. 

Key — Brodie's,  175. 
,,       Du  Bois-Reymond's,  160. 
,,       mercury,  162. 
,,       Morse,  162. 
„       plug,  163. 
„       spring  or  contact,  162. 
„       trigger,  163. 
Kjeldahl's  method,  127,  388. 
Knee-jerk,  321. 
Koenig's  flames,  317. 
Kreatin,  101. 
Kreatiniu,  132. 

Kiihne's  —  Curare    experiment,    132, 
194. 
„  nerve  current  experiment, 

242. 
„  eye,  350. 

,,  gastric  juice,  71. 

„  gracilis  experiment,  253. 

,,  muscle-press,  242. 

,,  pancreas  powder,  80. 

,,  sartorius  experiment,  19], 

Kiilz's  method  for  glycogen,  91. 
Kymograph,  301. 

Lact-albumin,  6,  95. 
Lactic  acid,  77. 
Lactoscope,  98. 
Lactose,  23,  95. 
Lambert's  method,  852. 
Lardacein,  11. 


Laryngoscope,  315. 
Latent  period  of  heart,  272. 

,,  reflex,  319. 

„  vagus,  276. 

Laurent's  polarimeter,  26. 
Lecithin,  103. 
Legal's  test,  146. 
Leucin,  82,  85. 
Lieben's  test,  146. 
Lieberkiihn's  jelly,  7. 
Liebermann's  reaction,  3. 
Liebig's  extract  of  meat,  101. 
Ligature,  effect  of,  285. 
Liquor  pancreaticus,  80. 

,,       pepticus,  72. 
Listing's  reduced  eye,  337. 
Lithates,  130. 
Liver,  extracts  of,  93. 
Load  on  muscle,  214. 
Locality,  sense  of,  367. 
Lud wig's  kymograh,  301. 

„        sphygmograph,  294. 
Lungs,  elasticity  of,  309. 
Lustre,  361. 
Lymph-hearts,  300. 
Lysatinin,  380. 
Lysin,  380. 


Magnesia  mixture,  113. 
Magnetic  tuning-fork,  222. 
Make  shocks,  171. 
Malt  extract,  70. 
Maltose,  22,  69. 

,,        estimation  of,  23. 

„        reducing  power,  23. 

,,        salivary  digestion,  69. 
Manometric  flames,  317. 
Marey's  myograph,  213. 

,,        sphygmograph,  291. 

,,       tambour,  228. 
Marriotte's  experiment,  337. 
Maximal  contraction,  198. 
Maxwell's  experiment,  340. 
Measures  of  capacity,  390. 

,,         length,  389. 
Meat,  extract  of,  101. 
Mechanical  stimulation,  181. 
Meiocardia,  291. 
Mercurial  key,  162. 
Metaphosphoric  acid,  138. 
Methaemoglobin,  52,  54. 
Methyl  violet,  76. 
Meyer  on  contrast,  356. 
Metronome,  222. 
Micro-spectroscopes,  17. 


398 


INDEX. 


Milk,  94. 

,,     caseinogen  of,  95. 
,,      coagulation  of,  97. 
,,      curdling,  of,  96. 
„      fat  of,  96. 
,,      gastric  juice  on,  75. 
„      lactalburain  of,  95. 
„      opacity  of,  98. 
,,      pancreatic  juice  on,  84. 
,,      to  peptonise,  75,  85. 
,,      rennet  on,  75. 
,,      salts  of,  97. 
,,      souring  of,  96. 
,,      sugar  of,  95. 
Milk-curdling  ferment,  96. 
Milk-sugar,  23,  95. 
Millon's  reagent,  2. 
Mineral  v.  organic  acids,  76. 
Minimal  contraction,  199. 
Mohr's  test,  77. 
Moist  chamber,  197. 
Molisch's  test,  22. 
Monosaccharides,  16. 
Moore's  test,  20. 
Morse  key,  162. 
Mosso's  ergograph,  230. 
Mucin,  14. 
Mucus  in  urine,  135. 
Mulberry  calculus,  152, 
Miiller's  valves,  312. 

,,       experiment,  295. 
Murexide  test,  128. 
Muscse  volitautes,  341. 
Muscarin  on  heart,  277. 
Muscle — Action  current  of,  237. 
action  of  heat,  214. 

,,         veratria,  214. 
curve  of,  203. 
demarcation  current,  234. 
direct  stimulation  of,  188. 
effect  of  load,  214. 

,,       two  shocks,  219. 
elasticity,  216. 
electrical  stimulation,  181. 
excitability,  192. 
extensibility  of,  226. 
extractives  of,  101. 
extracts  of,  100. 
fatigue,  223. 
independent  excitability  of, 

190. 
indirect  stimulation  of,  188. 
lever,  197. 
load,  214. 
on  mercury,  185. 
pigments  of,  102L 


Muscle — plasma  of,  102. 
press,  242. 
proteids,  102. 
reaction  of,  99. 
rupturing  strain,  189. 
serum,  102. 

single  contraction,  184,  197. 
sound,  189. 
stimulation  of,  183. 
successive  shocks  on,  219. 
temperature  on,  213. 
tension  of,  204. 
tetanus,  220. 
thickening  of,  228. 
twitch,  198. 
veratria  on,  214. 
wave,  226. 
work  of,  205. 
Muscular  contraction,  213. 
,,       load  on,  214. 
,,       sense,  370. 
,,       temperature  on,  213. 
,,        veratria  on,  214. 
Myelin -forms,  104. 

Myographic  experiments  on  man,  229. 
Myographs,  196. 

Blix's,  217. 
„  crank,  200. 

„  Fredericq's,  213. 

„  Marey's,  213. 

,,  pendulum,  206. 

spring,  208. 
Myosin,  7,  11,  102. 
Myosinogen,  100. 

Native  albumins,  4. 
Neef  s  hammer,  172. 
Negative  variation,  236. 

,,       after-images,  360. 
Nerve-muscle  preparation,  177,  179. 
Nerves — action  current,  238. 

cold  on,  257. 

demarcation  current,  237. 

double  conduction,  253. 

excitability  of,  192. 

fatigue  of,  225. 

localised  cold  on,  258. 

salt  on,  255. 

section  of,  256. 

unequal  excitability,  254. 

velocity  of  energy,  250. 
Neuramoebimeter,  326. 
Neuro-keratin,  14. 
Nicotin  on  heart,  277. 
Nitrites,  53. 

,,         in  saliva,  68. 
Nitrogen,  estimation  of,  888. 


INDEX. 


399 


Non-polarisable  electrodes,  233,  237. 
Normal  saline,  179. 

,,       soda  solution,  110. 

„       urobilin,  133. 
Nuclein,  103. 
Nucleo-albumin,  104. 

Ohm,  160. 

Oils,  chemistry  of,  29. 

Olein,  29. 

Ophthalmoscope,  364. 

Ophthalmotonometer,  367. 

Organic  acids  as  tests,  76. 

Organised  deposits  in  urine,  147. 

Ossein,  30. 

Ox-heart,  286. 

Oxalate  plasma,  36. 

Oxalate  of  lime,  152. 

Oxy- haemoglobin,  47. 

,,  crystals  of,  45, 

„  reduction  of,  49. 

,,  spectrum  of,  47,  49. 

Palmitin,  29. 

Pancreatic  action  on  fats,  83. 

,,  ,i     on  proteids,  81. 

,,  it     on  starch,  80. 

,,  digestion,  79. 

,,  extracts,  80. 

„         juice,  79. 

„  milk,  84. 

,,         peptones,  81. 
Paradoxical  contraction,  241. 
Paraglobulin,  38. 
Pavy's  solution,  144. 
Pea-meal,  99. 
Pendulum  myograph,  206. 
Pepsin,  72,  78. 
Peptones,  9,  74,  78. 

„         diffusibility  of,  10. 

,,        tests  for,  9. 

„         Witte's,  8. 
Peptonised  milk,  75. 
Peptonuria,  139. 
Perfusion,  279,  306. 
Perimetry,  344. 
Peripheral  projection,  369. 
Perrin's  eye,  365. 
Pettenkofer's  test,  88. 
Pfliiger's  law  of  contraction,  247. 
Phakoscope,  333. 
Phenol  in  urine,  134. 
„      tests  for,  146. 
Phenyl-glucosazon,  21. 
,,      tests  for,  146, 
„      hydrazin  test,  16,  21. 
„     maltosazoD,  22. 


Phloro-glucin  vanillin,  76. 
Phosphenes,  340. 
Phosphoric  acid,  ll.'>. 

,,  volumetric  process  for,115# 

Phosphorus,  test  for,  388. 
Physiological  apparatus,  list  of  makers 
of,  391. 
,,  rheoscope,  240. 

Picric  acid,  138. 
Picrocarmine,  spectrum  of,  64, 
Picro-saccharimeter,  144. 
Pigments  of  bile,  88. 

,,  urine,  134. 

Pilocarpin  on  heart,  277. 
Pince  myographique,  228. 
Piotrowski's  reaction,  2. 
Piston -recorder,  281. 
Pithing,  176. 
Plasma  of  blood,  36. 
,,       of  muscle,  102. 
,,       salted,  36. 
Plasmine,  36. 

,,         of  muscle,  102 
Plattner's  bile,  87. 
Plethysmograph,  295. 
Plug  key,  163. 

Pohl's  commutator,  165,  198. 
Poisons  on  heart,  277. 

,,      on  muscle,  214. 

,,      on  spinal  cord,  320. 
Polarimeters,  25. 
Polarisation  of  electrodes,  169. 
Polaristrobometer,  28. 
Polygraph,  289. 
Polysaccharides,  16. 
Positive  after-images,  359. 
Potassio-mercuric  iodide,  93. 
Potassium  bromide,  321. 
„         chloride,  821. 
,,         sulphocyanide,  68. 
Preformed  sulphuric  acid,  112. 
Pressure  sense,  369. 
Proteids,  1. 

,,        classification  of,  4. 

,,        coagulated,  10. 

„        general  reactions,  2. 

„        non-diffusibility,  3. 

,,        removal  of,  12. 

,,        rotatory  power,  28. 
Proteoses,  8,  73. 
Proto-albumose,  78. 
Ptyalin,  68. 
Pulse,  291. 
Pulse  wave,  296. 
Pupa,  367. 

,f     albino,  886. 


400 


INDEX. 


Pupil  reflex,  336. 
Purkinje's  figures,  341. 

,,         Sanson's  images,  280. 
Pus  in  urine,  147. 
Putrefactive   products    of    pancreatic 

digestion,  83. 
Pyrocatechin,  147. 
Pyuria,  147. 

Quantitative  estimation  of  acidity, 
110. 

„  „  chlorides, 

111. 

„  „         phosphates, 

115. 


143. 


135. 


sugar, 

urea,  120. 
uric  acid, 


Radial  movement,  350. 

Ragoiia  Scina,  356. 

Ranvier's  emulsion  experiment,  80, 

Reaction,  biuret,  9. 

„       of  Adamkiewicz,  3. 

„        of  Liebermann,  3. 

,,        of  Piotrowski,  2. 

,,       of  Utfelmaun,  77. 

,,        xantlioproteic,  2. 
Reaction -time,  323. 
Recording  apparatus,  194,  383. 
Reduced  alkali-haematin,  52. 

,,      haemoglobin,  48. 

,,  ,,         spectrum  of,  49. 

Reflex  action,  318. 
Rennet,  75. 
Repeated  shocks,  172. 
Respiration,  voluntary,  310. 

,,         on  pulse,  295. 
Respiratory  movements,  308. 

,,         of  frog,  311. 
Retinal  shadows,  341. 
Reverser,  166. 
Rheochords,  163,  245,  249. 
Rheometer,  298. 
Rheouome,  187. 
Rheoscopic  frog,  240. 
Rigor  mortis,  100. 
Ringer's  fluid,  280. 
Ritter's  tetanus,  249. 
Rosenthal's  modification,  198. 
Roy's  tonometer,  282. 

Saccharimeter,  148. 
Saccharoses,  16. 


Saliva,  67. 

,,      digestive  action  of,  68. 

,,      oxidising  power  of,  71. 
Salivary  digestion,  68. 
,,      effects  on,  69. 
Saponification,  30. 
Sartorius  of  frog,  186. 
Scheiner's  experiment,  331. 
Schiff's  test,  129. 
Secondary  contraction,  240,  241. 

,,       -Biedermann's  modification, 
243. 

,,        tetanus,  241. 
Semi-membranosus  and   gracilis  pre* 

paration,  179. 
Serum  of  blood,  35,  37. 

,,     proteids  of,  38. 

,,     to  obtain,  41. 
Serum,  salts  of,  40. 

,,       sugar  of,  40. 
Serum-albumin,  5,  38,  41,  136 

„       globulin,  6,  38,  41,  138. 

,,     -proteids,  38. 

,,       coagulation  of,  39. 
Shadows,  coloured,  358. 
,,         on  retina,  341. 
Shielded  electrodes,  168, 
Shunt,  234. 

Simple  muscle  curve,  202. 
Simultaneous  contrast,  354. 
Single  contraction,  185. 
Single  induction  shocks,  171. 
Size,  348. 
Skatol,  83. 
Smell,  370. 
Soap,  30. 

Soluble  albumin,  4. 
Soluble  starch,  69. 
Solubilities,  table  of,  383. 
Specific  rotation,  25. 
Spectroscope,  46. 
Spherical  aberration,  330. 
Sphygraographs,  291. 
Sphygmomanometer,  306. 
Sphygmoscope,  295. 
Spinal  nerve  roots,  322. 
Spirometer,  311. 
Spring  key,  162. 
Spring  myograph,  208,  213. 
Staircase,  271,  278. 
Stannius's  experiment,  270. 
Starch,  17. 

„       action  of  malt,  70. 

,,       animal,  19. 

,,      colloid,  18,  70. 

„      conversion  to  sugar,  22. 


INDEX. 


401 


Starch,  potato-,  18. 

„       soluble,  22. 

,,       stages  to  glucose,  22,  25. 

,,       stages  to  maltose,  69. 

,,       under  microscope,  17. 

,,       under  polariscope,  18. 
Steari!!,  29. 

Steele's  apparatus,  for  urea,  123. 
Stellar  {)hosphate,  114. 
Stereoscope,  361. 
Stethographs,  308. 
Stethometer,  310. 
Stethoscope,  286. 
Stimuli,  181. 
Stokes's  fluid,  49. 
Strasburger's  test,  88. 
Strobic  discs,  350. 
Struggle  of  fields  of  vision,  861. 
Strychnia,  320. 

Successive  light  induction,  358. 
Successive  shocks,  219. 
Sugar  in  urine,   estimation   of,   142, 

143,  145. 
Sugar  fermentation  method,  187. 

,,     tests  for,  142. 
Sulphocyanides,  68. 
Sulphur  test  for  bile,  88. 
Sui)rarenal  extract,  307. 
Swallowing  on  heart,  287,  312. 
Sympathetic  of  frog,  275. 

„  rabbit,  302. 

Syntonin,  8. 

Talbot's  law,  342. 

Tambour,  228. 

Tapping  experiment,  287. 

Taste,  370. 

Taurin,  90. 

Taurocholic  acid,  87. 

Telephone  experiment,  189. 

Temperature,  sense  of,  368. 

„  on  muscle,  218. 

Tendon,  to  rupture,  189. 
Tension  of  muscle,  204. 

„        recorder,  205. 
Test  meal,  79. 
Test  types,  282. 
Tetauomotor,  182. 
Tetanus,  220,  221. 

,,        secondary,  241. 
Tetra  paper,  71. 
Thermal  stimulation,  182. 
Thermometric  scales,  891. 
Time-markers,  210. 
Tissue-fibrinogen,  104. 
Tonometer,  282. 


Total  N.,  estimation  of,  127. 

Touch,  367. 

Trichloracetic  acid,  138. 

Trigger  key,  162. 

Tri])le  phosphate,  114. 

Trommel's  test,  20,  142. 

Tropaeolin,  76. 

Trypsin,  81. 

Tryptic  digestion,  81. 

Tubes,  rigid  and  elastic,  295,  298. 

Tiirck's  method,  319. 

Twitch,  185,  198. 

Tyrosin,  82,  86. 

Uffelmann's  reaction,  77. 
Unipolar  stimulation,  186. 
Unorganised  deposits  in  urine,  149. 
Urates,  130. 
Urea,  117. 
,,     nitrate,  117. 
,,     oxalate,  118. 
,,     preparation,  117. 
„     quantity,  119. 
,,     reactions  of,  119. 
,,     synthesis  of,  126. 
,,     volumetric  analysis,  120,  128 
Ureameter,  123,  126. 

„        of  Doremus,  123. 
Uric  acid,  127. 
,,    estimation  of,  135. 
,,   reactions,  128. 
„   salts  of,  130. 
,,  quantity,  127. 
,,   tests,  128. 
Urinary  calculi,  149. 

,,       deposits,  147,  149. 
Urine,  104. 

„      abnormal  constituents,  ISdL 
„     acidity,  107,  110. 
„      albumin  in,  136. 
„     alkalinity,  107. 
„      bile  in,  141. 
„      blood  in,  140. 
„     chlorides.  111. 
„     colour,  105. 
,     colouring-matters,  138. 
„     diabetic,  142. 
„     deposits  in,  147,  149. 
„      fermentations  of,  108. 
„      ferments  in,  185. 
,,     general  examination  of,  158. 
„     inorganic  bodies,  110. 
,,     mucus  in,  135. 
„     odour,  106. 
„     organic  bodies,  117. 
„     phenol  in,  184. 

20 


402 


INDEX. 


Urine,  phosphates  in,  112, 

,,      pigments  of,  134. 

,,      pus  in,  147. 

,,      quantity,  105. 

,,     reaction,  107. 

„     reactiosi  to  reagents,  135. 

„     solids  in,  106. 

,,      specific  gravity,  106. 

„      sugarin,  142. 

,,     sulphates  in,  111. 

„      transparency,  108. 

,,      urates  in,  130. 

„      urea  in,  117. 

,,     uric  acid  in,  127. 
Urinometer,  105. 
Urobilin,  133. 

febrile,  134. 

Vagus  of  frog,  273. 

„  ,,       latent  period  of,  275. 

„        rabbit,  302. 

,,         on  heart,  305. 
Valsalva's  experiment,  295. 
Valves  of  heart,  284. 
Vanillin,  76. 
Varnish,  197. 
Vascular  tonus,  279. 
Veratria,  214. 
Vibrating  reed,  211. 
Vision,  physiology  of,  329. 
Visual  axes,  349. 

,,     judgments,  347. 
Vital  capacity,  311. 
Vitellin,  7. 

Vogel's  lactoscope,  98. 
Volkmann's  experiment,  388. 


Volt,  160. 

Volumetric  process,  114. 

„  for       phosphorifl 

acid,  115. 

„  for  sugar,  143. 

„  for  urea,  120, 123 

Vomit,  examination  of,  79. 
Vowel-sounds,  317. 

Wave-lengths,  65. 

Wave  of  muscle,  228. 

Weber's  circles,  370. 

Weights,  390. 

Weyl's  test,  133. 

Wlieaten  flour,  98. 

Wheatstone's  fluttering  hearts,  830. 

Wheel  movements,  345, 

Whistle,  Galton's,  372. 

White  of  egg,  1,  2. 

Wild's  apparatus,  228. 

,,      polaristrohometer,  28. 
Wilke's  reagent  paper,  158. 
Witte's  peptones,  8. 
Wittich's  method,  71. 
Work  done  by  muscle,  205. 
Writing  point  of  Bayliss,  270. 

Xanthin,  101. 

,,         bodies,  381. 
Xanthoproteic  reaction,  SL 

Yellow  8p<ft,  340, 

Zollner's  lines,  847. 
Zymogen,  80. 


Bn  WSStK 


'5 


?s 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 

Los  Angeles 
This  book  is  DUE  on  the  last  date  stamped  below. 


'<. 


I     OCT  1  9  1964i 
I     OCT  1  9  RECO 

SEP22REtrtl 
0003911^28 


78 


""J^'  279 
SEP  2  8  1979 


969 


"orm  L9-6m-3, '54(3446)444 


'^•fi':'''^.-nr\u 


